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
The use of past perfect tense is incorrect in the sentence. Though “ a 1972 agreement” might tempt you to mark A, we have to understand the use of past perfect tense. Past perfect tense is used for the first event when there are two events.
The use of “had been allowed” means that it is not the case now. But there is no reason for us to believe that it is no longer the case now. Hence the use of past perfect tense is incorrect.
(B) reduced the phosphate amount that municipalities had been dumping
The use of past perfect continuous tense is incorrect. Past perfect continuous tense is used to talk about an action that started in the past, continued for a while (action in progress- ing form) and ENDED in the past.
(C) reduces the phosphate amount municipalities have been allowed to dump
We are talking about a 1972 agreement. We cannot use a simple present tense- reduces to talk about what was decided in the agreement. Eliminate.
(D) reduced the amount of phosphates that municipalities are allowed to dump
Generally, municipalities are allowed to dump x amount of phosphates into the Great Lakes. But a 1972 agreement reduced that amount.
The agreement between Canada and US reduced the amount of phosphates that municipalities are allowed to dump into the Great Lakes.
Correct.
(E) reduces the amount of phosphates allowed for dumping by municipalities