Whereas a ramjet generally cannot achieve high speeds without the init

Question

Whereas a ramjet generally cannot achieve high speeds without the initial assistance of a rocket, high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce airflow compression at the entrance of the engine and letting air pass through at supersonic speeds.

(A) high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce

(A) high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce

(B) that high speeds can be attained by scramjets, or supersonic combustion ramjets, is a result of their reducing

(C) the ability of scramjets, or supersonic combustion ramjets, to achieve high speeds is because they reduce

(D) scramjets, or supersonic combustion ramjets, have the ability of attaining high speeds when reducing

(E) scramjets, or supersonic combustion ramjets, can attain high speeds by reducing

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GMATNinja · Accepted Answer

By using the word “whereas”, the opening clause introduces a comparison between one clause and another. Because that portion of the sentence is not underlined, we must compare the fact that  a ramjet cannot achieve high speeds without assistance  to  something else .

As currently written, the sentence compares “a ramjet cannot achieve high speeds” to “high speeds can be obtained by scramjets.” This compares the fact that  ramjets cannot do something  with the fact that  high speeds can be attained by something else . Although it may not be 100% wrong, that comparison is definitely not as good as comparing what a  ramjet cannot do  to what a  scramjet can do .

Also, whatever immediately follows the parallelism trigger “and” should be parallel to something earlier in the sentence. In this case, the word “letting” is not parallel to anything earlier in the sentence. Logically, it should be parallel to “reduce”, but “reduce” is not parallel to “letting.” Instead, “reducing” would be parallel with “letting.”

But because (A) contains a less-than-ideal comparison and the parallelism is off, we can eliminate this answer choice.

(B) compares “a ramjet cannot achieve high speeds” to “that high speeds can be attained by scramjets.” As in (A), this comparison between the fact that a  ramjet cannot do something  and the fact that  high speeds can be attained by something else  is problematic.

Again, it would make sense to compare what a  ramjet cannot do  to a what a  scramjet can do . It would even make sense to compare how  high speeds cannot be attained  to how  high speeds can be attained . But (B) confuses the two. Eliminate (B).

(C) makes a mistake similar to the one found in (B). It compares that “a ramjet cannot attain high speeds” to “the ability of scramjets...is because....” It definitely does not make sense to compare  what a ramjet cannot do  to  WHY scramjet’s have a certain ability . Moreover, as in (A), “letting” is not parallel to anything earlier in the sentence.

In addition, “the ability... is because they reduce...” simply does not make much sense. Perhaps, scramjets  are able  because they reduce..., but scramjets’ ability is not “because” anything. Eliminate (C).

(D) fixes the comparison issues found in (A), (B), and (C). A ramjet is properly compared to scramjets. At first glance, it also looks like (D) correctly parallels “letting” to something found earlier in the sentence (“reducing”), and (D) does not seem to contain any definite errors.

Now let’s think about meaning. (D) says that “scramjets...have the ability of attaining high speeds  when  reducing...and letting....” The word “when” explains AT WHAT TIME scramjets have the ability to attain high speeds. In other words,  when scramjets reduce airflow compression , they can go fast. But what about  when they do NOT reduce airflow compression ? The author intends to explain HOW scramjets attain high speeds, not WHEN they do so.

There’s also some ambiguity in the parallelism. It seems like the author wants to say that scramjets have the ability of attaining high speeds when:

(1) REDUCING airflow compression at the entrance of the engine and 
(2) LETTING air pass through at supersonic speeds.

But it could also be read as if scramjets have the ability of:

(1) ATTAINING high speeds when reducing airflow compression at the entrance of the engine and 
(2) LETTING air pass through at supersonic speeds.

The fact that we have multiple ways to interpret the parallelism isn't ideal (especially since one of those ways does not seem to fit with the author's intentions). This is another vote against (D).

Finally, there are a couple issues with the phrase “have the ability.” First, idiomatically, scramjets “can attain high speeds” is simply more direct and clear than scramjets “have the ability of attaining high speeds.” But when we consider the literal meaning of the sentence, “able” implies agency, or the ability to act on one’s own behalf. And a scramjet, as an inanimate object, does not really possess agency and does not act on its own accord. So, a scramjet “can...”, but a scramjet does not really “have an ability.”

For all those reasons, we can eliminate (D).

Like (D), (E) corrects the comparison and parallelism issues found earlier in the sentence and contains no definite errors. The word “by,” as opposed to “when,” clearly shows that the author is explaining HOW scramjets attain high speeds. Also, by using “attain” rather than “attaining,” it is clear that “letting” is parallel to “reducing.”

(E) clears up the definite errors and meaning issues found in the previous choices, so it is the best answer choice.

GMATRockstar · Answer

https://www.youtube.com/watch?v=CsXSaUidN2c

carcass · Answer

Whereas a ramjet generally cannot achieve high speeds without the initial assistance of a rocket, high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce airflow compression at the entrance of the engine and letting air pass through at supersonic speeds.

(A) high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce

A) high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce

B) that high speeds can be attained by scramjets, or supersonic combustion ramjets, is a result of their reducing

C) the ability of scramjets, or supersonic combustion ramjets, to achieve high speeds is because they reduce

D) scramjets, or supersonic combustion ramjets, have the ability of attaining high speeds when reducing

E) scramjets, or supersonic combustion ramjets, can attain high speeds by reducing

after comma we need the subject to make the things clear. So A b and C are out

Comparing D and E

D the scramjets have the ability is ackward amd verbose

E is straight

aeglorre · Answer

I was confused about whether "by" in E is sufficient, or if we need another "by" before "letting". I guess what it boils down to is that both reducing and letting are being modified by "by", thus another "by" is superfluous. 
 
This reasoning was not why I eliminated B/D.. B is wrong because the structure makes no sense.. "that high speeds can be attained.. is a result of their reducing.. and letting", it just sounds awkward and wordy. It also distorts the intended meaning of the author.

D is gone because "have the ability of" does not look good.. "can attain" sounds much better. Also, as it stands right now, the meaning of the sentence is ambiguous. It implies that these jets only have the ability to attain high speeds when they reduce X and let Y... That's not the correct intent of the author. They always have the ability to attain high speeds, and that's BECAUSE they reduce X and let Y. The relationship is not conditional.

E is correct because "can attain" removes any ambiguity and is concise, "by" implies that "jets can attain high speeds because of THIS specific process", and therefore we know that the relationship is not conditional; the author simply wants to state a fact.

Again, my only gripe with E was that I was unsure if "by" should also be put before "letting", and this made me waste a whole minute on the problem, which was stupid considering the other options were riddled with errors.

Shiv2016 · Answer

The very first word 'WHEREAS' indicates that a comparison is coming our way.
'Ramjet' follows 'whereas', therefore the there should be a jet name after the comma to show comparison. Whereas high speeds follow 'comma' which is wrong construction.

After reading the sentence we know that there is a comparison between the high speeds of ramjet and other jet.

Choices A, B, and C are out based on this logic.

The other construction is 'Ramjets can....' and 'scramjets or supersonic combustion ramjets can......'.
'by reducing....and letting....' are parallel. 'AND' introduces a list and that list must be parallel and must make sense in the context of the sentence.

Thus E .

AnubhavK · Answer

"E" is the correct choice - Scramjets parallels a ramjet shows an effective contrast.

daagh · Answer

A) high speeds can be attained by scramjets, or supersonic combustion ramjets, in that they reduce---  can be attained is not be chosen when a more dynamic version 'can attain' is there in E.

B) that high speeds can be attained by scramjets, or supersonic combustion ramjets, is a result of their reducing ---  same issue as in A

C) the ability of scramjets, or supersonic combustion ramjets, to achieve high speeds is because they reduce --- T he ability to achieve is inferior as per - V-A -N.

D) scramjets, or supersonic combustion ramjets, have the ability of attaining high speeds when reducing ---  have the ability is inferior to can attain as per V-A- N.

E) scramjets, or supersonic combustion ramjets, can attain high speeds by reducing --  best fit.

NischalSR · Answer

daagh

Hello Sir! 
Can you please elaborate why C and D are wrong? I am not 100% sure why D is wrong and E is correct.

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Whereas a ramjet generally cannot achieve high speeds without the init

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Whereas a ramjet generally cannot achieve high speeds without the init

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