ans = D

A = idiom er as distinguish between X and Y is preffered over distinguish X from y

B = idiom er + structure er

C= Pn er = in which + they

D = idiom: distinguish between X and Y + use of relative pronoun = ok

E = structure er

Hey guys,

Interesting question - honestly, I think the distinction is pretty subtle so I'm not sure whether this would really make a phenomenal official question, but the lesson should have a takeaway for you.

One big point to make - the less you use the word "idiomatic" (or "idiom") the better you'll be as a test-taker. And when you're trying to distinguish by saying "this idiom is technically correct but the other is preferred" you're missing something. More often than not it comes back to logic and really thinking about the meaning of the sentence.

If I were to say "I distinguish Aquafina from Dasani water", that's a pretty limited statement without much value to the reader. There seem to be two different classes of an item and I'm simply indicating that I'm aware of that. That's not a great sentence. But if I added: I CAN distinguish Aquafina from Dasani --> Now that "CAN" tells a story...it suggests that it's somehow a unique trait to be able to make that distinction between similar items, so at least the sentence is going somewhere.

Similarly, if I were to say that "scientists distinguish between Aquafina and Dasani", that says something - it shows that scientists believe there is a distinct difference. The point of this sentence is to indicate that scientists make a special point to distinguish between two categories that you might think are identical, and that's a big (well, relatively big) deal.


So the real difference between A and D is the subtle difference in meaning. Choice A - ...distinguish X from Y - implies that there is a definite distinction and that, yes, scientists notice it. Choice D implies that there is something unique or compelling about the fact that scientists make a point to distinguish between the two, and that's a much more valid reason for writing this sentence.


Again, I think this may be too subtle to really justify an official GMAT question, but the lesson has a lot of value. Try to use the real nitty-gritty idioms as a last resort...we're just not great at picking up the tens of thousands of idiomatic subtleties in the English language. Logic and major-error categories are much more reliable.

David,
can you please explain the difference between D & E?