Critical Reasoning

Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae. Which of the following conclusions can properly be drawn from the information above?
A. The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior.
B. Host insects lack any effective defenses against the form of predation practiced by parasitic wasps.
C. Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species.
D. Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs.
E. Parasitic wasps use visual clues to calculate the size of a host egg

Pls provide explanations as OA is debatable. OA after some discussion

zaarathelab wrote:Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.

Which of the following conclusions can properly be drawn from the information above?

When the GMAT asks for an INFERENCE, the correct answer choice is WHAT MUST BE TRUE.

A. The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior. Correct. From the passage: Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. Since the host egg must be of SUITABLE size, the implication is that not ALL sizes are SUITABLE. Hence, the SMALLEST suitable size can be determined from the wasp's egg-laying behavior -- the smallest number of eggs that the wasp is able to lay -- indicating that this answer choice must be true.

B. Host insects lack any effective defenses against the form of predation practiced by parasitic wasps. Outside the scope. The passage offers no information about the defense mechanisms of the host insects. Eliminate B.

C. Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species. The passage states only that the wasps lay the proper number of eggs; it does not state that they learn this number FROM EXPERIENCE. Eliminate C.

D. Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs. The passage does not state which miscalculation -- too few eggs or too many -- would lead to death MORE QUICKLY. Eliminate D.

E. Parasitic wasps use visual clues to calculate the size of a host egg. The passage does not state how the wasps calculate the size of a host egg. Eliminate E.

The correct answer is A.

GMATGuruNY wrote:

zaarathelab wrote:Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.

Which of the following conclusions can properly be drawn from the information above?

A. The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior. This answer choice must be true. From the passage: Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. Thus, the number of eggs typically laid by a particular wasp -- THE WASP'S EGG-LAYING BEHAVIOR -- is sufficient information to determine THE SIZE OF THE SMALLEST HOST EGG that the wasp could parasitize.

B. Host insects lack any effective defenses against the form of predation practiced by parasitic wasps. Outside the scope. The passage offers no information about the defense mechanisms of the host insects. Eliminate B.

C. Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species. The passage states only that the wasps lay the proper number of eggs; it does not state that they learn this number FROM EXPERIENCE. Eliminate C.

D. Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs. The passage does not state which miscalculation -- too few eggs or too many -- would lead to death MORE QUICKLY. Eliminate D.

E. Parasitic wasps use visual clues to calculate the size of a host egg. The passage does not state how the wasps calculate the size of a host egg. Eliminate E.

The correct answer is A.

I guess I don't agree, though I see your point(s). And based on your many excellent previous solutions, I should know better than to disagree. But the passage essentially states that wasps adapt their egg-laying behavior to the size of the host egg. I.e. the size of the host egg determines their egg-laying behavior, rather than the other way around... "Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg." I'm keying in on any suitable size here. Then, the passage further states that disaster will strike if they either lay too few or too many eggs, which implies to me that they've learned (from experience) how many eggs to lay. And based on prior info, the number of eggs they lay should depend upon the size of the host egg.

So I guess I'd go with C. I do think A or C are the only two possible answers, but neither seem particularly obvious conclusions.

On the other hand, any suitable size could be taken to indicate that there is a minimum host egg size below which is unsuitable for parasitization. Then A becomes a reasonable conclusion as well.

chieftang wrote:

GMATGuruNY wrote:

zaarathelab wrote:Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae.

Which of the following conclusions can properly be drawn from the information above?

When the GMAT asks for an INFERENCE, the correct answer choice is WHAT MUST BE TRUE.

A. The size of the smallest host egg that a wasp could theoretically parasitize can be determined from the wasp's egg-laying behavior. Correct. From the passage: Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg. Since the host egg must be of SUITABLE size, the implication is that not ALL sizes are SUITABLE. Hence, the SMALLEST suitable size can be determined from the wasp's egg-laying behavior -- the smallest number of eggs that the wasp is able to lay -- indicating that this answer choice must be true.

B. Host insects lack any effective defenses against the form of predation practiced by parasitic wasps. Outside the scope. The passage offers no information about the defense mechanisms of the host insects. Eliminate B.

C. Parasitic wasps learn from experience how many eggs to lay into the eggs of different host species. The passage states only that the wasps lay the proper number of eggs; it does not state that they learn this number FROM EXPERIENCE. Eliminate C.

D. Failure to lay enough eggs would lead to the death of the developing wasp larvae more quickly than would laying too many eggs. The passage does not state which miscalculation -- too few eggs or too many -- would lead to death MORE QUICKLY. Eliminate D.

E. Parasitic wasps use visual clues to calculate the size of a host egg. The passage does not state how the wasps calculate the size of a host egg. Eliminate E.

The correct answer is A.

I guess I don't agree, though I see your point(s). And based on your many excellent previous solutions, I should know better than to disagree. But the passage essentially states that wasps adapt their egg-laying behavior to the size of the host egg. I.e. the size of the host egg determines their egg-laying behavior, rather than the other way around... "Parasitic wasps lay their eggs directly into the eggs of various host insects in exactly the right numbers for any suitable size of host egg." I'm keying in on any suitable size here. Then, the passage further states that disaster will strike if they either lay too few or too many eggs, which implies to me that they've learned (from experience) how many eggs to lay. And based on prior info, the number of eggs they lay should depend upon the size of the host egg.

So I guess I'd go with C. I do think A or C are the only two possible answers, but neither seem particularly obvious conclusions.

On the other hand, any suitable size could be taken to indicate that there is a minimum host egg size below which is unsuitable for parasitization. Then A becomes a reasonable conclusion as well.

On the GMAT, an inference is WHAT MUST BE TRUE. Interestingly, your focus on the word SUITABLE supports answer choice A but not answer choice C.

Answer choice A:
Since the host egg must be of SUITABLE size, the implication is that not ALL sizes are SUITABLE. Hence, the SMALLEST suitable size can be determined from the wasp's egg-laying behavior -- the smallest number of eggs that the wasp is able to lay -- indicating that answer choice A must be true.

Answer choice C:
The passage offers no information about HOW the wasp determines the proper number of eggs to lay. Although this ability could be learned from experience, it could also be innate. Thus, answer choice C does not have to be true.

Yes, I agree. I would have probably gone with my first instinct and chosen the wrong answer on this one. Clearly I need to get more familiar with what they are looking for in the CR questions!!

Although this ability could be learned from experience, it could also be innate. Thus, answer choice C does not have to be true.

Thanks Mitch. I guess the above is an important point that eliminates C

OA is A.

[quote="zaarathelab"][i]Although this ability could be learned from experience, it could also be innate. Thus, answer choice C does not have to be true.[/i]

Thanks Mitch. I guess the above is an important point that eliminates C

OA is A.[/quote]

I have also chosen C but yes the ability may be by born and does not come necessarily by experience, hence C is wrong. After that only A is a contender.

Hi Mitch,
Great EXPLANATION. Just couple of quick questions on the STIMULUS -

If they laid too many eggs in a host egg, the developing wasp larvae would compete with each other to the death for nutrients and space. If too few eggs were laid, portions of the host egg would decay, killing the wasp larvae. -- this part,I guess,is author's PREDICTION of TWO HYPOTHETICAL situations based on some SCIENTIFIC considerations/presumptions. Right ?

However, got a doubt on the above that if these situations haven't been witnessed in reality then is it really possible/realistic to conclude such consequences ?

Curious to know your thoughts!

RBBmba@2014 wrote:However, got a doubt on the above that if these situations haven't been witnessed in reality then is it really possible/realistic to conclude such consequences ?

Question stem:
Which of the following conclusions can properly be drawn from the information above?
The word in red implies that all of the statements in the passage are TRUE.
Thus, we should not question the validity of any statement in the passage.

Mitch - Thanks for your reply. But,I think, I didn't understand you clearly...

Would it be possible for you to be SPECIFIC to my couple of concerns raised above ? (Then I guess, I might be able to get what you wanted to convey!)

Please help.