Hey, gmat_perfect:

Good question, and, no, "so" is not a noun (or pronoun). So here is used as a form of "therefore" or "thus" to draw a conclusion - because Neanderthals had that vocal tract, therefore they were probably without language.

"So" is essentially a modifier here (an adverb) so* once you've established that it's a correct modifier (and it modifies "were", the verb, correctly) you can ignore it as it only serves to describe.

(*- see? There's "so" again as a modifier...just noticed that before hitting "submit")

Accordingly, the sentence without the modifier says:

Neanderthals had a vocal tract resembling an ape's and were probably without language...

"Neanderthals" is the subject of both past-tense verbs, "had" and "were", so the sentence structure is correct.

Neanderthals should be the subject of the sentence.
CDE out.

A uses "those" to refer to singlular "a vocal tract".

pick B

I have one question. What is the difference between ape's and apes'.
I thought apes' is the right possessive form.
Any thoughts?

Thanks Brain.

e-GMAT wrote:You are absolutely correct kvcpk in stating that apes' is the correct possessive form. Here is the difference between the two:

ape's vocal track - vocal track of an ape - singular
apes' vocal track - vocal tracks of apes - plural

Thus as a stand alone sentence, both these sentences are correct:

Neanderthals had a vocal tract resembling an ape's

The Neanderthals' vocal tracts resembled the apes'

I hope this answers your question.

With regards,

Payal

Perfect!! New learning today. Thanks for the help Payal.