I know there are few concepts tested in this question that is Modifiers, Parallelism and Sentence structure.
I can easily eliminate answer A, B, C and D but I still need more clarity with the overall construction of answer E for future reference.
Ans E says - "Chimpanzees are humans' closest relatives" which is an Independent Clause, followed by Adv-Modifiers and 'Comma + Conjunction + IC', but the parallel construction looks flawed, and the pronoun 'They' is also ambigous.
First the parallel Structure - "sharing 98% of the genetic DNA, leading complex social lives, eating both plants and animals" - the parallel rule says, the element should be arranged in a manner A and B if 2 items or A, B, and C if more than 2 Elements.
So the ideal parallel structure should be - sharing 98% of the genetic DNA, leading complex social lives, and eating both plants and animals.
The usage of Pronoun 'They' is hideous. Let's consider the 2nd clause as IC - they are handy with tools - Now "They" can refer to Relatives from the earlier clause or it can refer to the main subject 'Chimpanzees '. I don't think this kind of ambiguity is acceptable in GMAT.
But if you remove "They" then the the 2nd clause will be in parallel form i.e.
1. Chimpanzees are humans??? closest relatives, sharing 98% of the genetic DNA, leading complex social lives, and eating both plants and animals. (I have added 'AND' which is not present in the original answer choice E)
2 Chimpanzees are handy with tools . - Removed pronoun "They"
parallelism after verb 'ARE'.
Would appreciate if any expert can review and share his thoughts/comments.
Thanks,
Tilak