Sentence Correction

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

OE is

An agreement that occurred in 1972 is correctly described with the past tense verb reduced. Since the dumping continued after the date of the agreement, the past perfect verb had been allowed should instead be the present are allowed (if the agreement remained in eff ect when the sentence was written) or the past were allowed (if the agreement was no longer in eff ect when the sentence was written). Since were allowed does not appear in any of the options, we can assume that the correct verb tense is are allowed. The phrase amount of phosphates is clear and idiomatically correct, whereas phosphate amount is not idiomatic

A Had been allowed should be are allowed.

B The phosphate amount should be the amount of phosphates; the omission of some form of allow is incorrect since the agreement changed not the amount dumped, but the amount permitted to be dumped.

C Present tense reduces should be the past tense reduced; the phosphate amount should be the amount of phosphates; have been allowed should be are allowed.

D Correct. Th e past tense reduced is correctly used in this sentence to describe a past action, and the present tense are allowed is used to describe the present situation.

E Present tense reduces should be the past tense reduced; allowed for dumping is an incorrect idiom; allowed for dumping by municipalities is awkward