求教：XDF网络课堂的一道题，也是OG上的题，但是我不知道OG上的题号

To prevent some conflicts of interest, Congress could prohibit high-level government officials from accepting positions as lobbyists for three years after such officials leave government service. One such official concluede, However, that such a prohibition would be unfortunate because it would prevent high0level government officials from earning a livelihood for three years.

The oficials's conclusion logically depends on which of the following assumptions?

A. Laws should not restrict the behavior of former government officials.

B. Lobbyists are typically people who have previyously been high-level government officials.

C.Low-level gobernment officials do not often become lobbyists when they leave government service.

D.High-level gobernment officials who leave government service are capable of earning a livelihood only as lobbyist.

E. High-level government officials who leave government service are corrently permitted do act as lobbyists for only three years.

答案为B

但是我觉得该选D. 原文提到it would prevent high－level government officials from earning a livelihood for three years，答案B为正确答案的话，它如何起到推理加强，或者是桥梁作用呢？

请牛牛指点啊！