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.

While the new health insurance regulations may be onerous for large corporations, it can potentially be disastrous for small business owners, who in many cases will have to lay off employees in order to pay for the extended coverage.（）

A. it can potentially be disastrous for small business owners, who

B. they are potential disasters for small business owners, since

C. potentially they will be disastrous for small business owners, whom

D. for small business owners it is a potential disaster, because

E. they are potentially disastrous for small business owners, who