Hello!
Let's take a look at this question, one issue at a time, and narrow the options down to the right one! First, here is the original question, with the major differences between each option highlighted in orange:
A wave of new seltzer bars and bottle shops - all opened in the last two years, with some serving mostly alcoholic versions while others do not - are fueling interest in this formerly low-prestige beverage.
(A) with some serving mostly alcoholic versions while others do not - are
(B) with some serving mostly alcoholic versions and others not - are
(C) and some serving mostly alcoholic versions while others do not - is
(D) some serving mostly alcoholic versions and others not - is
(E) with some serving mostly alcoholic versions and others do not - is
After a quick glance over the options, a few key differences jump out:
1. with some / and some / some
2. and others not / while others do not / and others do not
3. is / are
Let's start with #3 on our list (is/are) because, regardless of which one we choose, it will eliminate 2-3 options right off the bat.
This is an issue of subject-verb agreement. The subject of the sentence is "A wave," which is singular. That means we MUST use a singular verb to match! Let's see how each option breaks down:
(A) with some serving mostly alcoholic versions while others do not - are
(B) with some serving mostly alcoholic versions and others not - are
(C) and some serving mostly alcoholic versions while others do not - is
(D) some serving mostly alcoholic versions and others not - is
(E) with some serving mostly alcoholic versions and others do not - is
We can eliminate options A & B because they use a plural verb (are) for a singular subject (A wave), which doesn't match!
Now, let's move on to #1 and #2 on the list. If we look at these together, it becomes an issue of parallel structure! Whenever it appears that the writer omits the verb from one half of the statement, it still needs to be parallel. The best way to check for that is to add the verb back in where it was omitted from. If it makes sense with the verb there, it's okay. If it doesn't make sense, it's not parallel. Let's take a close look at each option and figure out if they use parallel structure or not:
(C) and some serving mostly alcoholic versions while others do not - is
This is INCORRECT. If we add the verb back into the second half of the statement, we get this:
and some serving mostly alcoholic versions while others do not serving them --> WRONG
(D) some serving mostly alcoholic versions and others not - is
This is CORRECT. If we add the verb back into the second half of the statement, we get this:
some serving mostly alcoholic version and others not serving them --> RIGHT
(E) with some serving mostly alcoholic versions and others do not - is
This is INCORRECT. If we add the verb back into the second half of the statement, we get this:
with some serving mostly alcoholic versions and others do not serving them --> WRONG
There you have it - option D is correct because it uses proper subject-verb agreement and parallel structure!
I hope this helps!
Don't study for the GMAT. Train for it.
