大全284，不会呀，没讨论贴呀！(已解决)

1.        Even though the direct costs of malpractice disputes amounts to a sum lower than one percent of the $541 billion the nation spent on health care last year, doctors say fear of lawsuits plays major role in health-care inflation.

(A) amounts to a sum lower

(B) amounts to less

(C) amounted to less

(D) amounted to lower（C）

(E) amounted to a lower sum

哪位牛牛帮我看看，解释解释呀！为什么E不行？

我选C

不能说amounted to a lower sum than ..., 而应该说amounted to a sum lower than...

谢谢啊！晕头了！