Answer: D)like the Asian carp that are threatening to invade Lake Michigan, but far larger, more vicious, and mounted on four legs
There is generally agreement that feral swine are unwelcome - s<u>uch as the Asian carp that are threatening to invade Lake Michigan, but that are far larger, more vicious and mounted on four legs.</u>
Explanation: The task here is to replace the underlined clause with the correct option that would correctly complete the sentence, while also being precise.
A is the same as the underlined clause, and associates the Asian carp with feral swine by using "such as" as if it is an example of the feral swine. E also does this, therefore neither is the correct answer.
B uses the past perfect: have threatened, but the action has not been completed. For this reason, B is not the correct answer.
C and D are similar but D is more precise, making it the correct answer.