The most vexing problem faced by researchers exploring wind-powered

Hello expert, I have got down to C and E and eliminated C in a hurry but i want to know the strong reasons to eliminate E other than Which (that is referring to natural resource i guess)
@Veritasprepkarishma generis

In this case, "overload" is combined with the helping verb "does." "Does ... overload" agrees with the singular subject "that," which refers to "flow."

In (E), the relative clause "which meets ..." is misplaced. It is nowhere near what it is meant to modify, "flow."

Also, "how a constant flow ... can be achieved" is a poor way to state what "the most vexing problem" is. How a constant flow can be achieved is not really a problem.

This question is based on Parallelism and Construction.

The underlined portion of the sentence states the problem faced by the by researchers.

Idiomatically speaking, the noun phrase “how to achieve a constant flow of power from an unpredictable natural source” is better as the object or subject complement of the clause “the problem is” than the participle ‘achieving’. So, Option C, D, or E would be a better choice than Option A or B.

The last part of the sentence gives a description of ‘the flow of power’. Parallelism must be maintained in the description.

In Option A, the phrase “but so the flow does not overload…” is not parallel to the clause “that meets demand”. So, Option A can be eliminated.

Option B also lacks parallelism – the clause “which meets demand” is not parallel to the phrase “but without overloading”. So, Option B can be eliminated.

Parallelism is maintained in Option C. The verbs ‘meets’ and ‘does’ are parallel to each other in the modifier “a flow that meets demand but does not overload..”. So, C is the best of all the options.

In Option D, the verb ‘meets’ is not parallel to the participle ‘overloading’. Even if we accept that the last part is a participle modifier describing the flow, the conjunction ‘but’ is inappropriate since there is no contradiction implied in the sentence. The description of the flow merely adds some information. So, Option D can also be eliminated.

In Option E, the relative pronoun ‘which’ is placed too far away from its supposed antecedent ‘flow’ to be logically and grammatically correct as a relative pronoun refers to the word placed immediately before it. So, Option E also can be eliminated.

Therefore, C is the most appropriate option.

Jayanthi Kumar.

Bumping this thread- so AjiteshArun are you saying that the phrase following the comma "a flow that meets demand..." acts as a modifier for the previous phrase, similar to the functions of a "...ing" modifier? Thanks in advance!

Hi mag3184,

Yes, that modifier just provides us more information about a constant flow of power.

Hi CrackVerbalGMAT - what is the rule behind this? Or how do I just read up more on this? Asking because that was how I eliminated A and B but my elimination was more on common sense (a problem can't be achieving bla bla --- it has to start with a how or what)

GMATNinja - can you please explain your thought process for this question?

Isn't which referring to constant source of power?

According to egmat , "which" can modify a slightly far away noun. Here in this case for option E, I assumed 'which' is modifying constant flow of power from an unpredictable natural source . Where am I going wrong?

Poojita, for sure which can reach back but still there is some ambiguity here. Ambiguity isn't an absolute rule, but the option C is so much better. We don't even have to think too much in option C. The way I look at it, GMAT skills are applicable to the real world. In the real world, I'll never see 5 choices for writing a particular sentence. Going through all the choices, it's pretty clear that it's the flow which should meet demand. Option C just makes it far clearer than E. I couldn't spot an absolute error with E, but C does the job better.

Hope this helps!

Is there any other (stronger) reason to eliminate E?
That it is placed too far away from its supposed antecedent ('flow') is not a very strong reason for eliminating this option.

Plus, C is more wordy/lengthy (and sometimes people eliminate an option for being too wordy/awkwardly long) - "how to achieve a constant flow....., a flow that......" - repetitive use of the word "flow" just to make it doubly sure for the person reading it that it is the "flow" (and nothing else) that meets demand but does not overload. Normal samples of good written English (BBC, WSJ, Economist, etc.) do not usually contain instances of a word being used multiple times in the same sentence à la option C.

What I'm trying to get to here is that while I agree that Option C may be marginally more lucid (though at the cost of employing repetition) in conveying the meaning properly than Option E, is there a less debatable reason for selecting Option C than Option E having non-idiot proof usage/placement of the word "which"?

Actually this is a very strong reason to eliminate E; in fact, "which" modifies "source" in option E.


This is not redundant repetition; as you've mentioned, this repetition adds a lot of meaning clarity to the sentence and GMAT uses this quite extensively. You might want to Google resumptive modifier, to get more comfortable with this construct.

p.s. Our book EducationAisle Sentence Correction Nirvana discusses modifier issues of "which", their application and examples in significant detail. If you or someone is interested, PM me your email-id; I can mail the corresponding section.

a —> no parallel structure
b —> no parallel structure
c —> meets (parallel verb) but (parallel marker) does not overload (parallel verb)
d —> no parallel structure
e —> meets (parallel verb) but (parallel marker) does not overload (parallel verb)

C is better than E because E uses the passive voice and therefore it is wordier. C is definitely more clear than E.

Hello from the GMAT Club VerbalBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.