Critical Reasoning

In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly, and genetic mutations occurred at random in the populations. These experiments show that all genetic mutation is random.

Which one of the following, if true, enables the conclusion to be properly drawn?

(A) Either all genetic mutations are random or none are random.

(B) The bacteria tested in the experiments were of extremely common forms.

(C) If all genetic mutations in bacteria are random, then all genetic mutations in every other life form are random also.

(D) The kind of environment in which genetic mutation takes place has no effect on the way genetic mutation occurs.

(E) The nutrients used were the same as those that nourish the bacteria in nature

what would be cthe correct answer if this was an assumption question?

By the way, OA is A is it beacuse this is draw a conclusion question?

Thank you ALL in advance!

Hi,
This is not a 'draw the conclusion' question. This comes under 'Justify the conclusion'. It is something like a strengthener, but so strong that it is sufficient to prove the conclusion when added to the premises.
To Solve this apply : Premises + Answer choice = Conclusion.

Frankenstein wrote:Hi,
This is not a 'draw the conclusion' question. This comes under 'Justify the conclusion'. It is something like a strengthener, but so strong that it is sufficient to prove the conclusion when added to the premises.
To Solve this apply : Premises + Answer choice = Conclusion.

What do u think about the word "environment" referring to here??? i believe environment refers to "generous supply of nutrients" here. Op D seems good to me...what do u think???

Now, as the original poster asked about the assumption i believe Op D should be the assumption.

Hi,
Yes. D seems to be the assumption.

Frankenstein wrote:Hi,
Yes. D seems to be the assumption.

How can u justify Op A as the answer of original question. It look strange but even for the original one, i'm bit confused b/w Op A and Op D. Can u explain, why Op D cannot be the answer of the original question????

gmat25 wrote:

Frankenstein wrote:Hi,
Yes. D seems to be the assumption.

How can u justify Op A as the answer of original question. It look strange but even for the original one, i'm bit confused b/w Op A and Op D. Can u explain, why Op D cannot be the answer of the original question????

Hi,
Original question - Justify. Means it is a sufficient condition i.e. if the option is correct Conclusion is valid. Using the answer choice as support, we make the conclusion valid.
We can denote this as Answer choice Correct --------------------------> Conclusion Valid

Modified question - Assumption. Means it is a necessary condition i.e. if the conclusion is valid, the assumption is correct. We take the conclusion as valid and then try to find out what could be the assumption.
We can denote it as Conclusion Valid ----------------------> Assumption True.
That is the reason if we negate assumption, conclusion will not hold. Just as if p ->q, not q -> not p.

From op D, we can only say that environment does not have impact on the mutation. The kind of bacteria selected can have impact as well right? So, we cannot conclude that all mutations are random. Op A actually forms a bridge between mutation of certain bacteria being random and all mutations being random.

Frankenstein wrote:

gmat25 wrote:

Frankenstein wrote:Hi,
Yes. D seems to be the assumption.

How can u justify Op A as the answer of original question. It look strange but even for the original one, i'm bit confused b/w Op A and Op D. Can u explain, why Op D cannot be the answer of the original question????

Hi,
Original question - Justify. Means it is a sufficient condition i.e. if the option is correct Conclusion is valid. Using the answer choice as support, we make the conclusion valid.
We can denote this as Answer choice Correct --------------------------> Conclusion Valid

Modified question - Assumption. Means it is a necessary condition i.e. if the conclusion is valid, the assumption is correct. We take the conclusion as valid and then try to find out what could be the assumption.
We can denote it as Conclusion Valid ----------------------> Assumption True.
That is the reason if we negate assumption, conclusion will not hold. Just as if p ->q, not q -> not p.

@Frank

I already understood the meaning of both "Assumption" and "justify"...but still i believe Op D can be the potential answer for original question. see below i insert Op D in the argument as an added premise and i feel that its actually working. see below.


In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly, and genetic mutations occurred at random in the populations. Since, The kind of environment in which genetic mutation takes place has no effect on the way genetic mutation occurs, These experiments show that all genetic mutation is random.

Your call????

Hey.. I have just added that point in my previous post. That might help.

On second thought , if the author wanted to use the premise that the environment had no effect on the mutation , why would he take pains to ensure that the bacteria is provided with nutrients .

Side ques:Can mutations occur at random in more than 1 way ?
For example : mutation could occur randomly in hexagonal form by fission
mutation could also occur randomly in octagonal form by fusion

In experiments in which certain kinds of bacteria were placed in a generous supply of nutrients, the populations of bacteria grew rapidly, and genetic mutations occurred at random in the populations. Since, The kind of environment in which genetic mutation takes place has no effect on the way genetic mutation occurs, These experiments show that all genetic mutation is random.