646. Since 1986 enrollments of African Americans, American Indians, and Hispanic Americans in fulltime engineering programs in the United States has steadily increased, while the number of other students who enter the field has fallen.(A) has steadily increased, while the number of other students who enter the field has fallen
(B) has steadily increased, while other students entering the field have declined in number
(C) increased steadily, while there was a decline in the number of other students entering the field
(D) have steadily increased, while the number of other students entering the field has fallen
(E) have steadily increased, while that of other students who enter the field fell

Can someone please explain why the answer is D instead of E?
thanks.

Choice E has two fatal flaws:
* The construction 'that of', normally such a darling of the GMAT writers, doesn't have an antecedent here at all. It attempts to refer to 'enrollments', but 'enrollments' is plural.
* 'Fell' is in simple past tense. This doesn't make a lot of sense to start with (because we're talking about a time interval from 1986 to the present), but it's especially bad here because it's nonparallel with the present perfect tense in the other half ('has ... increased').

Choice D doesn't have either of these problems.
* You may have balked at the fact that choice D introduces a new word ('number'), which seems to clash with 'enrollment'. This doesn't violate parallelism, though: both are nouns, and the verbs are kept in the same tense.

Can you please tell me what is the problem with answer choice C?

I analysed this question as follows:


Since an adverb describes a verb, in all the choices other than C, the adverb 'steadily' modfies the verb 'increased'.so i chose option 'C' .

Thanks,
A J

Option C's major flaw is that it uses the simple past tense ("increased" and "was") when it should use the present perfect ("have increased" and "has fallen"). Why is that? Well, because the sentence is describing something that has been occurring since 1986 and continues until now. Using the past tense would imply that this enrollment trend is no longer occurring.

To your point about "steadily": In fact, steadily is used correctly in all five options to modify verbs. In A & B, it modifies "has increased," in C it modifies "increased", and in D & E it modifies "have increased." So this is not a good word on which to base eliminations.

Rey