IMO E

Only choice that is parallel

A is out because it compares singular to plural

B, C and D are looks awkward

OA?

The answer is B ..But please explain .

senthil wrote:The answer is B ..But please explain .

526. Neanderthals had a vocal tract that resembled those of the apes and so were probably without language, a shortcoming that may explain why they were supplanted by our own species.
(A) Neanderthals had a vocal tract that resembled those of the apes
(B) Neanderthals had a vocal tract resembling an ape’s
(C) The vocal tracts of Neanderthals resembled an ape’s
(D) The Neanderthal’s vocal tracts resembled the apes’
(E) The vocal tracts of the Neanderthals resembled those of the apes

B addresses the two issues we need to address.
1. Comparison ... vocal tract <-> those !
2. "and so were" ... needs to point to Neanderthals.

526. Neanderthals had a vocal tract that resembled those of the apes and so were probably without language, a shortcoming that may explain why they were supplanted by our own species.

The pronoun they must refer unambiguous to Neanderthals so we need the noun ape in the singular form so we can eliminate A D E (moreover those not agree with the singular "vocal tract").
C introduce the plural vocal tracts that makes ambiguous the referent of thay that must refer unambiguous to Neanderthals.
Therefore, the answer is B.