The following questions present a sentence

问题：

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.

After leaving the Pentagon, MacTaggart could have profited from his connections with defense contractors, but he refused to do so.（）

A. After leaving the Pentagon, MacTaggart could have profited from his connections with defense contractors, but he refused to do so.

B. MacTaggart could have profited from his connections with defense contractors after leaving the Pentagon, but he refused to do it.

C. MacTaggart could have profited after leaving the Pentagon from his connections with defense contractors, but he refused to do so.

D. Having left the Pentagon, MacTaggart could have used his connections with defense contractors to profit, but he refused to do it.

E. Refusing to profit from his connections with defense contractors, MacTaggart could have done so after leaving the Pentagon.