As a result of surging economic indicators, most analysts

Dear akhil911,
I'm happy to help. In truth, I don't think this is the greatest SC question. Here's the text again:
As a result of surging economic indicators, most analysts upgraded the company’s stock to a strong “buy”, ignoring the advice of the head of a watchdog organization who warned that the company’s product would prove not only dangerous but ineffective in the long run
(A) who warned that the company’s product would prove not only dangerous but
(B) warning that the company’s product would prove not only dangerous and also
(C) warning that the company’s product would prove itself to be both dangerous and
(D) who warned that the company’s product would prove to be both dangerous and
(E) who was warning that the company’s product would prove not only dangerous but
The structure "not only ... but also" is the standard, but many grammar authorities also accept "not only ... but" as well. I don't think the real GMAT would ask you to choose between these two, because it's not a black/white, right/wrong absolute split. The fact that this question predicates the answer on this split is, in fact, a poor indication for the quality of the question.

Even if (D) is preferable, (A) is not clearly wrong, and so it can't be decisively eliminated. I would say the problem is: this question is faulty. All SC questions on the real GMAT, and all high quality GMAT SC practice question, will have one clearly correct answer and four other choices, each one with something absolutely unambiguously wrong about it. That is the high standard the GMAT keeps, and this particular question falls abysmally short of this standard.

The problem is not you. The problem is the flawed nature of the question itself. Here's a book review you may find instructive:
https://magoosh.com/gmat/2013/1037-pract ... ok-review/

Let me know if you have any further questions.
Mike

This topic is about idioms. If we use, "not only..." make sure the form is "not only X but also Y". All of the answers above fail to do so. If we use "both" make sure it is in the form "both X and Y" - only D does so. Therefore clear shot for D.

IMHO (D)

Correct idiomatic form : Both X and Y is used

As a result of surging economic indicators, most analysts upgraded the company’s stock to a strong “buy,” ignoring the advice of the head of a watchdog organization who warned that the company’s product would prove not only dangerous but ineffective in the long run.

(A) who warned that the company’s product would prove not only dangerous but [Not only... But also... is presented incorrectly ]

(B) warning that the company’s product would prove not only dangerous and also [Not only... But also... is presented incorrectly ]

(C) warning that the company’s product would prove itself to be both dangerous and [ incorrect placement of ING Verb ]

(D) who warned that the company’s product would prove to be both dangerous and [who warned is the correct reflexive pronoun]

(E) who was warning that the company’s product would prove not only dangerous but [Not only... But also... is presented incorrectly ]


Please correct if any explanation is wrong.

A. correct explanation. not only...but... is wrong - also is required to complete the idiom.
B. correct explanation. not only...and also... is wrong - but is required in place of and.
C. The reflexive pronoun itself is wrongly used. A reflexive pronoun is used when the subject and the object are the same. Here the implication is that the product is both the subject and the object of the verb prove.
D. correct explanation... just note that who is not a reflexive pronoun, but a relative pronoun (though for GMAT you do not need to know the correct names of the various pronoun types)
E. correct explanation. not only...but... is wrong - also is required to complete the idiom.
Moreover the usage of past continuous is inappropriate. Past continuous is used to depict an action in past that was happening in the background the same time when some other action happened in the past (the latter expressed in simple past).
Shyam came back home while it was raining.
Coming is an event in past that happened while another event raining was occurring in the background. Past continuous is generally not used in isolation in GMAT.

Was able to drill down to two options, C and D.

Between C and D, D is correct as C uses the word "itself"

The correct idiom, well the most concise and correct idiom, is "both x and y"

D

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