In this sentence, there's a comparison between two types of mammoths; the imperial mammoths wiped out by climate change and the mammoths that were in the earlier period which was wiped out by human predators.

Option A - correct
This correctly compares because it uses "as" which allows the writer use an affirmative verb "were" which sets up a clear contrast between how both mammoths were wiped out.

Option B - incorrect
The pronoun "that" used in the sentence is wrong. If it used "those", it would have passed across the intended meaning of the sentence.

Option C - incorrect
It says that the imperial mammoths were wiped out in an earlier period whereas it was another race of mammoths that were wiped out in the earlier period.

Option D - incorrect
This option says that earlier periods were wiped out by human predations; this deduction is incorrect.

Option E - incorrect
This says that the imperial mammoths were like the mammoths wiped out by human prdations. It doesn't compare the fact that there are two different mammoths wiped out in two different ways.