大全一道题，释疑！

1.        A 1972 agreement between Canada and the United States
                    reduced the amount of phosphates that municipalities had been allowed to dump into the Great Lakes.

(A) reduced the amount of phosphates that municipalities had been allowed to dump

(B) reduced the phosphate amount that municipalities had been dumping

(C) reduces the phosphate amount municipalities have been allowed to dump

(D) reduced the amount of phosphates that municipalities are allowed to dump

(E) reduces the amount of phosphates allowed for dumping by municipalities

OG的答案是D，到底是A还是D呢？我个人偏向A的，请大家指教！

我也偏向A  不知道这里为什么一定要用一般现在时态 过去完成时态逻辑含义合理

这题好像很久之前讨论过的，试试在这里找找吧

http://forum.chasedream.com/dispbbs.asp?boardID=23&ID=81938&page=1

记得以后贴出题目给出题号，以便大家帮忙寻找