Hello Everyone!
This looks like a great example of a question that deals with both idiom structures and parallelism! To start, here is the original question, with major differences between the options highlighted in orange:
Doctors generally agree that such factors as cigarette smoking, eating rich foods high in fats, and alcohol consumption not only do damage by themselves but also aggravate genetic predispositions toward certain diseases.
(A) not only do damage by themselves but also aggravate
(B) do damage by themselves but also are aggravating to
(C) are damaging by themselves but also are aggravating
(D) not only do damage by themselves, they are also aggravating to
(E) are doing damage by themselves, and they are also aggravating
After a quick glance over the options, there are 2 main things we can focus on:
1. Parallelism: damage/aggravate & damaging/aggravating
2. Idiom Structure: not only X, but also Y
Let's start with #1 on our list: parallelism. No matter which structure you end up using later on, both verbs need to be written using the same structure. Parallel structure is clearer, easier to read, and looks more professional - all things the GMAT loves! Here's how each option holds up:
(A) not only do damage by themselves but also aggravate
(B) do damage by themselves but also are aggravating to
(C) are damaging by themselves but also are aggravating
(D) not only do damage by themselves, they are also aggravating to
(E) are doing damage by themselves, and they are also aggravating
We can eliminate options B, D, & E because the verbs they use aren't parallel. Now, let's focus on #2 on our list: idiom structure. The idiom structure we're using here should look like this:
not only X but also Y
Let's see how each option handles this:
(A) not only do damage by themselves but also aggravate
This is CORRECT! It follows the "not only X but also Y" idiom structure, and both X and Y are written using parallel structure!
(C) are damaging by themselves but also are aggravating
This is INCORRECT because it doesn't use the "not only X but also Y" structure. It's missing the "not only" part. You could fix this by replacing the "but also" with "and" to make it clearer for readers.
There you go - option A was the correct choice all along!
Don't study for the GMAT. Train for it.
