Sentence Correction

OG PG. 732 #95

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

Correct answer is:
C

I read a lot of other threads on this question, but couldn't find one that truly provides a comprehensive explanation on the differences between C and E. Grammatically, I believe E is also right because "they" correctly refers to the antecedents, "crests and trough." The only thing I can nitpick about E is a possible change in meaning. (IE: crests and trough that remain stationary vs. a stationary crest and trough.) However, I don't think the change in meaning is really significant. To me comparing "crests and trough that remain stationary vs. a stationary crest and trough" is like comparing "a car that runs on electricity" vs. "an electric car." Appreciate your inputs. Thanks!

the one is so obvious --> C and E are the only forms to coordinate S-V linkage here. In E semantically stationary cannot be used as a modifier for crests ans troughs - it will make illogical inference of the crests to be stationary?

OneTwoThreeFour wrote:OG PG. 732 #95

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

Correct answer is:
C

I read a lot of other threads on this question, but couldn't find one that truly provides a comprehensive explanation on the differences between C and E. Grammatically, I believe E is also right because "they" correctly refers to the antecedents, "crests and trough." The only thing I can nitpick about E is a possible change in meaning. (IE: crests and trough that remain stationary vs. a stationary crest and trough.) However, I don't think the change in meaning is really significant. To me comparing "crests and trough that remain stationary vs. a stationary crest and trough" is like comparing "a car that runs on electricity" vs. "an electric car." Appreciate your inputs. Thanks!

I believe it's the change in meaning, basicly the modifier stationary is wrong in E:

(C) crests and troughs that remain stationary
although the air that forms them is moving
rapidly, is

This means that although the air that forms the crest and troughs is moving rapidly, they remaing stationary ...

(E) stationary crests and troughs although they are
formed by rapidly moving air, is

This means crest and troughs that are stationary (so.. they don't move?) although they are formed by rapidly moving air...

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

-- crests and troughs are not stationary, but they remain stationary.
In E, they refers to = stationary crests and troughs, this is logically wrong.

In C, them refers to crests and troughs, this is correct.
... the air that forms them ... = correct, the air that forms the crests and troughs ...

OneTwoThreeFour wrote:OG PG. 732 #95

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

Correct answer is:
C

I read a lot of other threads on this question, but couldn't find one that truly provides a comprehensive explanation on the differences between C and E. Grammatically, I believe E is also right because "they" correctly refers to the antecedents, "crests and trough." The only thing I can nitpick about E is a possible change in meaning. (IE: crests and trough that remain stationary vs. a stationary crest and trough.) However, I don't think the change in meaning is really significant. To me comparing "crests and trough that remain stationary vs. a stationary crest and trough" is like comparing "a car that runs on electricity" vs. "an electric car." Appreciate your inputs. Thanks!

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).

Agree with tetura84 .

The meaning conveyed makes the diffrence , which makes GMAT questions bit challenging specially for non native test takers.

------The crest and trough that remain stationary although air forming them is moving at speed .

------The stationary crest and trough although the air forming them is moving at speed.

In 2nd sentence the word although doesn't make much sense .

GMATGuruNY wrote:

OneTwoThreeFour wrote:OG PG. 732 #95

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

Correct answer is:
C

I read a lot of other threads on this question, but couldn't find one that truly provides a comprehensive explanation on the differences between C and E. Grammatically, I believe E is also right because "they" correctly refers to the antecedents, "crests and trough." The only thing I can nitpick about E is a possible change in meaning. (IE: crests and trough that remain stationary vs. a stationary crest and trough.) However, I don't think the change in meaning is really significant. To me comparing "crests and trough that remain stationary vs. a stationary crest and trough" is like comparing "a car that runs on electricity" vs. "an electric car." Appreciate your inputs. Thanks!

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 stationery (verb) and is moving rapidly (verb).

Thanks Mitch . I could not explain it technically , the key is parallelism .

Thanks Mitch!

It took me a while to realize the contrast between "stationary" and "are formed." Working on GMAT SC really makes me yearn the days of SAT, in which half of the errors are due to obvious double-negatives.