Hello ankursethi297,

I would be glad to help you with this query.

Let's take a look at Choice D: the brain growth in mice when placed in a stimulating environment or the increase in canaries' neurons when they

The pronoun they in this choice grammatically refers to neurons, suggesting that the neurons learn new songs. Logically, they must refer to canaries'. But because canaries' appears in this choice in possessive form, the non-possessive pronoun they cannot refer to the possessive noun canaries' because possessive nouns act as an adjective.

Also, this choice seems to suggest that the brain growth in mice is placed in a stimulating environment. This meaning is certainly illogical.


Hope this helps.
Thanks.
Shraddha
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dear GMAT Ninja
I got this wrong. But, after that I find the use of WHEN is incorrect in all the first four options. Will it be deterministic error or can we really eliminate all 4 on the basis of wrong use of WHEN.

I had a theory in mind when I was solving this question.
Complex gerunds can be parallel with action nouns only, and not with simple gerunds or concrete nouns. Examples of production of brain cells qualifies as action noun, and therefore can be parallel with a complex gerund or action noun only.
Does the answer satisfy the above theory?
DmitryFarber ChrisLele egmat sayantanc2k daagh

I'm skeptical of the use of "when" in this problem. Formally, "when" is used as a conjunction or adverb. Informally, "when" can be used as a relative pronoun in place of "at which" or "during which" (see here).

If "when" is perceived as a conjunction, then the original sentence might read like this: "When placed in a stimulating environment, recently documented examples of neurogenesis, the production of new brain cells, include the brain growing in mice". This clearly is not what we want.

If "when" is perceived as a relative pronoun, then according to the Cambridge Dictionary it isn't fulfilling its function of replacing "at which" or "during which". And thus, it's being used in some way that most grammar authorities don't agree is acceptable even for informal usage.

These concerns are important to note, but probably not enough to eliminate the options that use "when". GMAT can sometimes use language that is more informal than most grammar authorities agree is acceptable.

A more important concern is that if we assume "when" is being used as a relative pronoun, then which noun is "when" modifying? In (A) "when" could be modifying "brain growing" or "mice". We don't know because there is no verb to tell us like there is when using "that" ("that are" in (E) indicates we are modifying "mice" and not "brain growth").

Finally, in option (E) both examples use "that" rather than one using "when" and the other using "that". This creates mild parallelism that probably isn't enough to tip the scale in favor of (E) by itself but it's a nice bonus and we can feel better about choosing (E).

we need 2 examples of the PRODUCTION of new brain cells.

B/
mice and canaries are not examples of the PRODUCTION of brain cells.

C/
mice's brains and canaries' neurons are not examples of the PRODUCTION of brain cells (rather, they are examples of the brains or brain cells themselves).

... as opposed to the correct answer
E/
brain growth and an increase in neurons absolutely ARE examples of the PRODUCTION of new brain cells.
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Hi Jay, when looking for parallelism, we should not look at word on word similarity; for example, in option E, the presence of an in one phrase does not necessitate the presence of an in the other phrase.

The structure of option E is:

...include brain growth in mice ...or an increase in neurons...

Both the bold parts are Noun-phrases, and hence parallel.
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