Sentence Correction

Well, you haven't stated the source of the question. Is this an official question? If not, then you cannot hope that it will be exactly like other GMAT questions.

You don't like the comma before the but also. I get it. However, all options contain that comma. This doesn't mean that I don't agree with your contention that every GMAT SC question I have seen doesn't include that comma.

The real question is this: Can we learn something from this problem that will let us do well on the real GMAT test? If the answer is yes, then let's learn it and move on without worrying too much. If someone prepares for a marathon by riding his bike, and it works for him, then who are we to say that it's wrong?

This question contains a known idiom: NOT ONLY x BUT ALSO y. We must determine that each sentence contains the right idiom and that it is parallel.

Options (A) and (C) are reasonably parallel. Option B offers us NOT ONLY published BUT ALSO he hosted... the "he" is redundant and ruins the parallelism. Option (D) offers us NOT ONLY several popular books BUT ALSO hosting. Option (E) offers us NOT ONLY publish BUT ALSO in hosting.

Our goal, then, is to distinguish between option A and option C. What differences do you see? Option A offers the verb "hosted" whereas option C offers the phrase "was the host of." Option A offers us the phrase "for which he was" whereas option C offers us the phrase "for that he was."

It is clear that (A) is better than (C).