An Interesting Grammar Problem

[gtest]

Q. 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 have marked the answer as E, but the answer is C. The explanation is that it's incorrect to introduce a dependent adverbial [i]although[/i] clause into a prepositional phrase (with crests ...). I could not make much sense out of it. Can someone help me with it ?

[aim-wsc]

eliminate A, B & D because of 'are'

disclamer: I wont discuss technical details, adverbial, clause blah-blah... & hv not solved SC problems in months. :mrgreen:
but
E doesn't show contradition in statement by using 'although'
C does it perfectly. 8)

[aim-wsc]

eliminate A, B & D because of 'are'

disclamer: I wont discuss technical details, adverbial, clause blah-blah... & hv not solved SC problems in months. :mrgreen:
but
E doesn't show contradition in statement by using 'although'
C does it perfectly. 8)

[mayonnai5e]

See my blog post today for an explanation:

https://www.beatthegmat.com/viewtopic.php?p=20585#20585

[BTGmoderatorRO]

going by the options given in this question,
Option B is giving a reverse of the statement. Therefore it is not correct.

Option A uses the plural 'are' to describe the 'standing waves' which I think is a wrong decision.

Option D is of the same analysis and expression as option A

Option E does not give a good sentence construction.

Option C "crests and trough" that remain stationary although the air that forms them is moving rapidly, is". This option gives a clear cut analysis to the question, the use of Verb 'is' to show that 'air' is singular and 'standing waves' should not be pluralized. Thus Option C remains the correct option