Scientists now suspect that imperial mammoths of the Pleistoscene peri

Answers B, C, and D are ridiculous.

• MEANING?
mykrasovski is spot on.
We need meaning to be clear.

Two kinds of mammoths were wiped out by different causes. The sentence emphasizes that people eradicated one kind but not the other kind.
(1) imperial Pleistocene period mammoths = Imperial Mammoths
were wiped out by climate, NOT by human predation.

(2) mammoths of an earlier period = Earlier Period Mammoths WERE wiped out by human predation.

• ANALYSIS

I am already inclined towards (A).

True, in a sense, we are comparing nouns (two kinds of mammoths). The preposition "like" is good for comparing nouns.

But we are really comparing what happened to those nouns.
(We are not comparing, say, the adjectivial qualities of burritos and sandwiches.)

The sentence emphasizes what caused the eradication of each kind of mammoth.

The negated verb creates issues that are resolved better by (A).

AS allows us to use an affirmative verb that sets up clear contrast:

Earlier Period Mammoths WERE [wiped out by human predation],
whereas
Imperial Mammoths were NOT wiped out by human predation

• Compare (A) and (E)

(A) ... Imperial mammoths of the Pleistoscene period were wiped out not by human predation, as were mammoths of earlier periods, but by climate change.

(E) ... Imperial mammoths of the Pleistoscene period were wiped out not by human predation, like the mammoths in an earlier period, but by climate change.

Oh, wow. Read (E) a couple of times.
(E) suggests that the Imperial Mammoths were like the Earlier Period mammoths.

Look at this sentence:
The rosebush was killed not by sunlight, like the moss, but by bugs.
-- Both the rosebush and the moss were not killed by sunlight?
-- The rosebush is like the moss?

I can make sense out of (E). But I am working too hard.

Option A?

(A) ... imperial mammoths of the Pleistocene period were wiped out not by human predation, as were mammoths of earlier periods, but by climate change.

The structure is a little hard to follow.
I will move the second WERE and tack on the rest of the verb, which is tacit.

Imperial mammoths of the Pleistocene period were wiped out not by human predation, as mammoths of earlier periods WERE [wiped out by human predation], but by climate change.

So
(1) Imperial mammoths of the Pleistocene period were not wiped out by human beings, but
(2) mammoths of earlier periods were wiped out by human beings.

That contrast is what we need.

The answer is (A).

mykrasovski , I hope that analysis helps. The sentence structure is odd and a bit convoluted, which may explain why (E) seems as attractive to you as (A) does.

I do not think that both A and E are correct.
At the least, (A) is better than (E).

GMATNinja, see mykrasovski above, please?
And I am never, ever going to eat calamari.
Broccoli and sleep phobia? Cakewalk by comparison.
I do suggest the truffle pasta at Scalinatella Restaurant in Manhattan . . . I think they have a grilled octopus appetizer. My pals enjoyed it. I don't like sharks either.
Where was I?

Oh. The answer is (A).




**If we switch from passive to active voice, it may be easier to see that the comparative focus is on an event:
-- Human predation wiped out Earlier Period Mammoths.
-- Human predation did NOT wipe out Imperial Mammoths. Climate did.