The following questions present a sentence

题目：

The following questions present a sentence, part of which or all of which is underlined. Beneath the sentence, you will find five ways of phrasing the underlined part. The first of these repeats the original; the other four are different. If you think the original is best, choose the first answer; otherwise choose one of the others.

These questions test correctness and effectiveness of expression. In choosing your answer, follow the requirements of standard written English; that is, pay attention to grammar, choice of words, and sentence construction. Choose the answer that produces the most effective sentence; this answer should be clear and exact, without awkwardness, ambiguity, redundancy, or grammatical error.

Nile perch, voracious predators that will eat anything smaller than themselves, are natives of northern Africa but were introduced to Tanzania’s Lake Victoria in a foolhardy attempt during the 1960s of boosting the local sport-fishing industry; since their introduction, these sturdy fish have decimated most other aquatic species in the lake.（）

A. are natives of northern Africa but were introduced to Tanzania’s Lake Victoria in a foolhardy attempt during the 1960s of boosting

B. are native in northern Africa but were introduced to Tanzania’s Lake Victoria during the 1960s as foolhardy attempts to boost

C. are native to northern Africa but were introduced to Tanzania’s Lake Victoria during the 1960s in a foolhardy attempt to boost

D. had been native to northern Africa but during the 1960s were introduced to Tanzania’s Lake Victoria in a foolhardy attempt to boost

E. are native to northern Africa but were introduced to Tanzania’s Lake Victoria as a foolhardy attempt of boosting