When rates were raised in 1985, postal service officials predicted they would make further rate increases unnecessary for at least three years.
A. they would make further rate increases unnecessary
B. they would mean that further rate increases would not be needed
C. that it would not be necessary for further rate increases
D. that the increase would make further rate increases unnecessary
E. further rate increases will not be needed
Very nice discussion indeed.
This question is somewhat testing your knowledge of English idioms. (C) is an attractive answer but it is idiomatically incorrect for this simple reason: "it is necessary for" must be followed by a person, a group of people, or some type of organization, not by an object or an abstraction.
Yes, (D) seems wordy but it is the correct answer. Adding "the increase" into the sentence does not make the sentence (I am stressing that point here) redundant but, rather, makes it clear.
Conciseness is the last thing you should worry about, as concise answers are always full of traps.
First and foremost, be grammatically correct and semantically clear.
The best sentence is not included in the answer choices as it would be evident to most of you and thus will not add any significant point value (as a reward) to the GMAT score of the more verbally inclined among you.