OG 10 question

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OG 10 question

by hey_thr67 » Mon May 21, 2012 9:00 pm
The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over them; the resulting flow pattern, with crests and troughs that remain stationary although the air that forms them is moving rapidly, are known as "standing waves."

(A) crests and troughs that remain stationary although the air that forms them is moving rapidly, are
(B) crests and troughs that remain stationary although they are formed by rapidly moving air, are
(C) crests and troughs that remain stationary although the air that forms them is moving rapidly, is
(D) stationary crests and troughs although the air that forms them is moving rapidly, are
(E) stationary crests and troughs although they are formed by rapidly moving air, is

I am not able to understand the grammar, explained in OG, behind the right answer that is C
Source: — Sentence Correction |

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by ronnie1985 » Mon May 21, 2012 11:29 pm
The subject is "FLOW PATTERN" which is singular
Hence (C)
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by hey_thr67 » Tue May 22, 2012 1:38 am
So is E.. Experts please reply...

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by GMATGuruNY » Tue May 22, 2012 5:58 am
hey_thr67 wrote:The peaks of a mountain range, acting like rocks in a streambed, produce ripples in the air flowing over them; the resulting flow pattern, with crests and troughs that remain stationary although the air that forms them is moving rapidly, are known as "standing waves."

(A) crests and troughs that remain stationary although the air that forms them is moving rapidly, are
(B) crests and troughs that remain stationary although they are formed by rapidly moving air, are
(C) crests and troughs that remain stationary although the air that forms them is moving rapidly, is
(D) stationary crests and troughs although the air that forms them is moving rapidly, are
(E) stationary crests and troughs although they are formed by rapidly moving air, is

I am not able to understand the grammar, explained in OG, behind the right answer that is C
In A, B and D, are (plural) does not agree with its subject pattern (singular). Eliminate A, B and D.

In E, a contrast is made between stationary (adjective) and are formed (verb). An adjective cannot be compared to a verb. Eliminate E.

The correct answer is C.

In C, the comparison is parallel: a contrast is made between remain (verb) and is moving (verb).
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