nox104 wrote:I say B is better because it is concise and parallel :

data .. are useful mainly for gauging the storm’s structure and strength, not for the speed and path of its movement.

Stacey Koprince wrote:I received a PM asking me to respond to this question. Whoever originally posted, check the OA - I don't think it's B.

Yes, "not" is a coordinating conjunction, just like "and." You don't need both. So that eliminates D and E.

Most people seem to be interpreting the core structure as this:
The data <modifier> are useful [for X, not for Y]

X: gauging the storm's structure and strength
Y: ?? (that's the question)

The main word in X is "gauging." None of the answer choices (Y) give us an "ing" word for parallelism... so that core structure I typed up above is not actually the core structure here. (Note: it could've been, if they'd written the answer choices accordingly... they just didn't.)

Instead, this must be the core:
The data <modifier> are useful mainly for gauging [X, not Y]
X: the storm's structure and strength
(main words: structure and strength)
Y: ??

The only answer choice that does NOT use "for" and does not use "and" is C. And the main words there are "speed and path," which are appropriately parallel to "structure and strength."

Be careful where you get your study material. Even for well-written questions (like this one), when people post them online, there will be typos in the OAs and that sort of thing. You don't want to "study" something that isn't actually right!

gmat009 wrote:

nox104 wrote:I say B is better because it is concise and parallel :

data .. are useful mainly for gauging the storm�s structure and strength, not for the speed and path of its movement.

OA is B ...