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 a 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
关于last year的修饰问题：even though last year...这样就知道last year 是修饰整个分句，但是放在分句句末我觉得会产生修饰the nation spent on health care 的歧异？
这样的话，若B项 改成：amout to less.就不知道该选B还是C？
牛牛指教！ | 
