Critical Reasoning

Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.
Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?
(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
(C) Some species become extinct because of accumulated gradual changes in their local environments.
(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
(E) Species that are widely dispersed are the least likely to become extinct

Why C is wrong/right here?also explain reasons for A and B

ssgmatter wrote:Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.
Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?
(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
(C) Some species become extinct because of accumulated gradual changes in their local environments.
(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
(E) Species that are widely dispersed are the least likely to become extinct

Why C is wrong/right here?also explain reasons for A and B

Let me elaborate my question a bit more here

Actually I feel that option C also points toward the patterned extinction but my point of confusion is why it is wrong in one go.....

Hope my question makes some sense here

ssgmatter wrote:Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.
Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?
(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
(C) Some species become extinct because of accumulated gradual changes in their local environments.
(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
(E) Species that are widely dispersed are the least likely to become extinct

Why C is wrong/right here?also explain reasons for A and B

Step 1 of the Kaplan Method for CR: focus on the question stem

We identify an "explain" question. We know that there's going to be seemingly contradictory facts in the stimulus and our task is to reconcile the apparent discrepancy.

Step 2 of the Kaplan Method for CR: untangle the stimulus

Going in, we know there's going to be a contradiction; we're on the lookout for contrast keywords to identify it.

Sure enough, there's a "however" in the stimulus, separating the seemingly contradictory facts. Paraphrasing the two parts of the discussion:

1) lots of variables in extinction which affect different species in different ways. Author thinks that this should lead to random extinctions.

BUT

2) in reality, extinctions follow a definite pattern with many species dying out all at once.

Step 3 of the Kaplan Method for CR: think about/predict an answer

It's very difficult to predict a precise answer for Explain questions, so we just make sure we understand the task: the correct choice will provide a common sense reason why the two facts presented in the stimulus coexist.

Step 4 of the Kaplan Method for CR: attack the choices

Since we don't have a clear prediction, we need to consider each choice, thinking "does this reconcile the facts?"

a) well, if (a) is true, then that explains why so many species disappear all at once. Very strong contender.

b) this choice makes the second fact even more bizarre. If (b) is true, then the author's original prediction seems far more likely than what actually happens. Accordingly, (b) is a "180" (opposite of what we're looking for) - eliminate!

c) this choice doesn't address either issue (mass extinctions and definite pattern) - eliminate!

d) geologically recent times? What does that have to do with explaining the fossil record? Eliminate!

e) this choice doesn't address either issue - eliminate!

Only (a) offers even a partial explanation - choose (a).

Stuart Kovinsky wrote:

ssgmatter wrote:Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.
Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?
(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
(C) Some species become extinct because of accumulated gradual changes in their local environments.
(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
(E) Species that are widely dispersed are the least likely to become extinct

Why C is wrong/right here?also explain reasons for A and B

Step 1 of the Kaplan Method for CR: focus on the question stem

We identify an "explain" question. We know that there's going to be seemingly contradictory facts in the stimulus and our task is to reconcile the apparent discrepancy.

Step 2 of the Kaplan Method for CR: untangle the stimulus

Going in, we know there's going to be a contradiction; we're on the lookout for contrast keywords to identify it.

Sure enough, there's a "however" in the stimulus, separating the seemingly contradictory facts. Paraphrasing the two parts of the discussion:

1) lots of variables in extinction which affect different species in different ways. Author thinks that this should lead to random extinctions.

BUT

2) in reality, extinctions follow a definite pattern with many species dying out all at once.

Step 3 of the Kaplan Method for CR: think about/predict an answer

It's very difficult to predict a precise answer for Explain questions, so we just make sure we understand the task: the correct choice will provide a common sense reason why the two facts presented in the stimulus coexist.

Step 4 of the Kaplan Method for CR: attack the choices

Since we don't have a clear prediction, we need to consider each choice, thinking "does this reconcile the facts?"

a) well, if (a) is true, then that explains why so many species disappear all at once. Very strong contender.

b) this choice makes the second fact even more bizarre. If (b) is true, then the author's original prediction seems far more likely than what actually happens. Accordingly, (b) is a "180" (opposite of what we're looking for) - eliminate!

c) this choice doesn't address either issue (mass extinctions and definite pattern) - eliminate!

d) geologically recent times? What does that have to do with explaining the fossil record? Eliminate!

e) this choice doesn't address either issue - eliminate!

Only (a) offers even a partial explanation - choose (a).

Thankyou Stuart for the exhaustive explanation.

Stuart Kovinsky wrote:

ssgmatter wrote:Extinction is a process that can depend on a variety of ecological, geographical, and physiological variables. These variables affect different species of organisms in different ways, and should, therefore, yield a random pattern of extinctions. However, the fossil record shows that extinction occurs in a surprisingly definite pattern, with many species vanishing at the same time.
Which of the following, if true, forms the best basis for at least a partial explanation of the patterned extinctions revealed by the fossil record?
(A) Major episodes of extinction can result from widespread environmental disturbances that affect numerous different species.
(B) Certain extinction episodes selectively affect organisms with particular sets of characteristics unique to their species.
(C) Some species become extinct because of accumulated gradual changes in their local environments.
(D) In geologically recent times, for which there is no fossil record, human intervention has changed the pattern of extinctions.
(E) Species that are widely dispersed are the least likely to become extinct

Why C is wrong/right here?also explain reasons for A and B

Step 1 of the Kaplan Method for CR: focus on the question stem

We identify an "explain" question. We know that there's going to be seemingly contradictory facts in the stimulus and our task is to reconcile the apparent discrepancy.

Step 2 of the Kaplan Method for CR: untangle the stimulus

Going in, we know there's going to be a contradiction; we're on the lookout for contrast keywords to identify it.

Sure enough, there's a "however" in the stimulus, separating the seemingly contradictory facts. Paraphrasing the two parts of the discussion:

1) lots of variables in extinction which affect different species in different ways. Author thinks that this should lead to random extinctions.

BUT

2) in reality, extinctions follow a definite pattern with many species dying out all at once.

Step 3 of the Kaplan Method for CR: think about/predict an answer

It's very difficult to predict a precise answer for Explain questions, so we just make sure we understand the task: the correct choice will provide a common sense reason why the two facts presented in the stimulus coexist.

Step 4 of the Kaplan Method for CR: attack the choices

Since we don't have a clear prediction, we need to consider each choice, thinking "does this reconcile the facts?"

a) well, if (a) is true, then that explains why so many species disappear all at once. Very strong contender.

b) this choice makes the second fact even more bizarre. If (b) is true, then the author's original prediction seems far more likely than what actually happens. Accordingly, (b) is a "180" (opposite of what we're looking for) - eliminate!

c) this choice doesn't address either issue (mass extinctions and definite pattern) - eliminate!

d) geologically recent times? What does that have to do with explaining the fossil record? Eliminate!

e) this choice doesn't address either issue - eliminate!

Only (a) offers even a partial explanation - choose (a).

Very Nicely Explained .
Thanks
I want to ask you one thing. I always have a problem with biological problems, like species, some decease all those subject which are some how related to medical stream. I does not matter whether it is a strengthen, weaken, or assumption or any other, I am just not able to understand them fully.
Do you have any kind of suggestion for me on these problem.

goyalsau wrote: Very Nicely Explained .
Thanks
I want to ask you one thing. I always have a problem with biological problems, like species, some decease all those subject which are some how related to medical stream. I does not matter whether it is a strengthen, weaken, or assumption or any other, I am just not able to understand them fully.
Do you have any kind of suggestion for me on these problem.

You should do some general reading in the area - not with the intent of learning content (you certainly don't need to know any science for the GMAT), but with the goal of familiarizing yourself with the style of writing and vocabulary used.

Since GMAT science passages fall into the "popular science" category, reading National Geographic or Scientific American will give you a good sample of GMAT-style science passages.

got it...