Discussion of greenhouse effects have usually had as a focus the

Question

Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,  but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.

(A) Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,

(B) Discussion of greenhouse effects has usually had as its focus whether Earth would get warmer and what the extent would be,

(C) Discussion of greenhouse effects has usually focused on whether Earth would grow warmer and to what extent,

(D) The discussion of greenhouse effects have usually focused on the possibility of Earth getting warmer and to what extent it might,

(E) The discussion of greenhouse effects has usually focused on whether Earth would grow warmer and the extent that is,

https://www.nytimes.com/1995/05/23/science/more-extremes-found-in-weather-pointing-to-greenhouse-gas-effect.html

Discussion of the greenhouse effect has usually focused on the question of whether the earth will warm and by how much ; scientists believe a doubling of greenhouse gas concentrations would raise the average global temperature by 3 to 8 degrees Fahrenheit. But climatologists have said all along that the most obvious effects, and those that will have the largest impact on people, would be extremes of temperature, precipitation and storminess.

Greenhouse Effects

(A) Subject-Verb ( discussion have ); Parallelism ( X and Y )

(B) Meaning

(C) CORRECT

(D) Subject-Verb ( discussion have ); Parallelism ( X and Y )

(E) Parallelism ( X and Y )

First glance

The opening split is between  discussion  and  the discussion —not a very significant distinction. In this case, the first glance is not particularly helpful.
 
  Issues

(1) Subject-Verb:  discussion have

The first part of the original sentence reads  Discussion have had...   Discussion  is a singular subject but the verb  have  is plural.

Scan the other answers to find any that repeat this error. Eliminate answers (A) and (D).

(2) Parallelism ( X and Y )

Meaning

The underlined portion contains an X and Y structure, so check the parallelism.

(A) ...the possibility of Earth growing warmer and to what extent it might...

(B) ...whether Earth would get warmer and what the extent would be...

(C) ...whether Earth would grow warmer and to what extent...

(D) ...the possibility of Earth getting warmer and to what extent it might...

(E) ...whether Earth would grow warmer and the extent that is...

This is a very unusual structure. It’s tough to identify the parts of speech of some of the words, so focus on whatever you do know. The original sentence pairs the plain noun  possibility  with something that’s not a plain noun:  to what extent . Nouns should be parallel to nouns, so eliminate choice (A). Answer (D) repeats this same error.

Answer (E) also pairs a plain noun ( extent ) with something that is not a plain noun ( whether ); eliminate (E), too.

Answers (B) and (C) both pair words that aren’t plain nouns and, in both cases, these words can properly be made parallel. Answer (C) might sound funny, but note for future that it is acceptable to say  whether  (something will happen) and  to what extent  (that thing will happen).

Answer (B) has a meaning issue. Answer (C) makes clear that the second half of the parallel part refers to growing warmer: whether Earth would grow warmer and to what extent (it would grow warmer).

In choice (B), though, what does  what the extent would be  mean? It could mean “what would the extent of the greenhouse effects be?” or it could mean “what would the extent of the warmer temperatures be?” Answer (C) is better because there is only one possible meaning. Eliminate choice (B).

The Correct Answer

Correct answer (C) pairs a singular subject and verb:  discussion has . It also presents a parallel structure with unambiguous meaning:  whether Earth would grow warmer and to what extent  (it would do so).

Note: If you used the root phrase concept from the Sentence Correction Strategy Guide to evaluate the parallelism and are wondering how answer (C) can be correct, note that this problem is an exception to the normal rule. The root phrase works with the first item but does not work with the second item:

...has usually focused on whether Earth would get warmer

...has usually focused on to what extent (!!!)

Treat this overall expression as an idiom:  whether X (will happen) and to what extent . This expression is acceptable as long as the root phrase works with the first ( whether ) item.

SC04093

mikemcgarry · Accepted Answer

Dear zoezhuyan , How are you, my friend? Once again, these are astute questions, and I am happy to respond. :-)

While (B) has other problems, the structure about which you ask is 100% correct without the word " on ." The structure is . . . to have as my X Y . . . The X , the object of the preposition " as ," indicates a role or function, and Y is the person or thing that fulfills that role or function. The verb could also be "hold" or some related verb of possession. I have as my friend the police chief in town. I have as my primary mode of transportation a mountain bike. I hold as my ideal the teachings of Zen. I treasure as my favorite movie Casablanca . I have as a question in my mind whether zoezhuyan will understand my explanation. In the last example, the Y is not a simple noun but a substantive clause , a full clause that takes the role of a noun. That's precisely what is happening in (B). The X is the word " focus " and the Y is a substantive clause. This is perfectly correct. Now, about the parallelism in (C)--remember, first of all, that parallelism is not a grammatical structure, but a logical structure, and the grammar simply follows the logic and supports it. Think about "question clauses"--these are substantive clauses that represent the indirect statement of a question. My question is what the right answer might be. My question is what his name is. My question is whether it will rain. My question is how fall she can throw a baseball. My question is to whom should I make the check payable. My question is for whom was the symphony written. My question is against whom is he arguing. My question is in what does she really believe? The words " who " and " what " serve as relative pronouns. They open subordinate clauses, in these causes substantive clause that are acting as nouns. Like all pronouns, relative pronouns can be the object of a preposition, even when they open a subordinate clause. Notice, incidentally, in American colloquial English, many speakers will avoid these sophisticated constructions by ending the sentence with a preposition. My question is whom should I make the check payable to. My question is whom was the symphony written for. My question is whom is he arguing against. My question is what does she really believe in? In the big world of grammar, this is controversial issue. Many intelligent people would say that it's perfectly fine to end a sentence with a preposition: these people are taking a more grammatically liberal position. Others, such as I, are grammatically conservative and are appalled but such structures. That's the spectrum in the big world of grammar. Now, in the much more limited world of the GMAT, the GMAT SC tends to be quite conservative grammatically. I have never seen an official prompt whose OA had a sentence or clause ending in a preposition; this questionable structure appears rarely, and only on incorrect answer choices--that is, choices that are clearly incorrect for other reasons. The GMAT seems to disapprove of this structure but never tests is directly. Thus, from the information in (C), we could say: Discussion of greenhouse effects has usually focused on whether Earth would grow warmer. Discussion of greenhouse effects has usually focused on to what extent Earth would grow warmer. Each one of those sentences is correct on its own, and it sounds clumsy and redundant to state them separately in a side-by-side way like this. What (C) has is an exceptionally sleek and elegant combination. Logically, these are both questions, so the parallelism between them is perfect. Does all this make sense? Have a wonderful day, my friend. :-)

Mike

EMPOWERgmatVerbal · Answer

Hello Everyone!

Let's tackle this question, one issue at a time, and get to the correct choice as quickly as we can! Before we dive in, let's take a quick glance over the original question and options, highlighting any major differences between the options in  orange :

Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,  but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.

(A)  Discussion  of greenhouse effects  have  usually  had as a focus   the possibility of  Earth growing warmer and  to what extent it might,  
(B)  Discussion  of greenhouse effects  has  usually  had as its focus   whether  Earth would get warmer and  what the extent would be,  
(C)  Discussion  of greenhouse effects  has  usually  focused on   whether  Earth would grow warmer and  to what extent,  
(D)  The discussion  of greenhouse effects  have  usually  focused on   the possibility of  Earth getting warmer and  to what extent it might,  
(E)  The discussion  of greenhouse effects  has  usually  focused on   whether  Earth would grow warmer and  the extent that is,

After glancing over things quickly, it's clear we have several ways we can attack this question:

1. Discussion / The discussion -->  wordiness/meaning 
2. have / has -->  subject-verb agreement 
3. had as a focus / had as its focus / focused -->  wordiness 
4. to what extent / to what extent it might / to what extent it would be / to what extent that is -->  parallelism/wordiness

Whenever you see this many issues to focus on, start with the one you feel most confident in tackling first.  That way, you can rule out wrong answers more quickly - and if you're lucky, you won't have to deal with the grammar issues you're less comfortable with!

If you look carefully, we have 3 items on the list that deal with wordiness, and 1 item that deals with subject-verb agreement.  Let's start by tackling the subject-verb agreement item (have/has), so we can eliminate 2-3 wrong options right away.

The subject of the sentence is either "Discussion" or "The discussion," both of which are  singular  subjects that require the  singular  verb "has" to match. Let's see how each option stacks up:

(A) Discussion of greenhouse effects  have  usually had as a focus the possibility of Earth growing warmer and to what extent it might, 
(B) Discussion of greenhouse effects  has  usually had as its focus whether Earth would get warmer and what the extent would be, 
(C) Discussion of greenhouse effects  has  usually focused on whether Earth would grow warmer and to what extent, 
(D) The discussion of greenhouse effects  have  usually focused on the possibility of Earth getting warmer and to what extent it might, 
(E) The discussion of greenhouse effects  has  usually focused on whether Earth would grow warmer and the extent that is,

We can eliminate options A & D because they don't use proper subject-verb agreement.

Now, let's move on to one of the wordiness topics: has had a focus / had as its focus / focused. The GMAT encourages writers to use concise language whenever possible, and to eliminate any overly wordy phrases they can find. Since the phrases "has had a focus" and "had as its focus" mean exactly the same as simply saying "focused," let's eliminate any remaining options that are overly wordy:

(B) Discussion of greenhouse effects has usually  had as its focus  whether Earth would get warmer and what the extent would be, 
(C) Discussion of greenhouse effects has usually  focused  on whether Earth would grow warmer and to what extent, 
(E) The discussion of greenhouse effects has usually  focused  on whether Earth would grow warmer and the extent that is,

We can eliminate option B because it is overly wordy.

Now we're only left with 2 options. Let's take a closer look at each option to figure out which is the better choice.

(C)  Discussion  of greenhouse effects  has  usually  focused  on whether Earth would grow warmer and  to what extent ,

This is  CORRECT ! It uses concise language wherever possible (Discussion/focused), and the phrase that begins with "whether" is written using parallel formatting (whether Earth would grow warmer and to what extent  ).

(E)  The discussion  of greenhouse effects  has  usually  focused  on whether Earth would grow warmer and  the extent that is ,

This is  INCORRECT  for a couple reasons. First, it's overly wordy to say "The discussion" when "Discussion" means the same thing. Second, the phrase "whether Earth would grow warmer and the extent that is  " doesn't make sense because it's not written using parallel formatting.

There have it - option C is the correct choice because it has proper subject-verb agreement, uses concise language, and uses parallel structure!

Don't study for the GMAT. Train for it.

ExpertsGlobal5 · Answer

Dear Friends,

Here is a detailed explanation to this question-

Concepts tested here: Subject-Verb Agreement + Parallelism + Tenses + Awkwardness/Redundancy

• Any elements joined by a conjunction ("and" in this sentence) must be parallel.
• Future actions are conveyed through the simple future tense. 
• The simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature.

A:  This answer choice incorrectly refers to the singular noun "Discussion" with the plural verb "have...had". Further, Option A fails to maintain parallelism between "the possibility of Earth growing warmer" and "to what extent it might"; remember, any elements joined by a conjunction ("and" in this sentence) must be parallel. Additionally, Option A uses the passive voice construction "had as a focus the possibility of Earth growing warmer", leading to awkwardness and redundancy.

B:  This answer choice uses the passive voice construction "had as its focus", leading to awkwardness and redundancy.

C:   Correct.  This answer choice correctly refers to the singular noun "Discussion" with the singular verb "has...focused". Further, Option C correctly maintains parallelism between "whether Earth would grow warmer" and "to what extent". Additionally, Option C avoids the tense error seen in Option E, as it uses the noun phrase "to what extent" rather than a phrase that includes an active verb, such as "is" in Option E. Besides, Option C is free of any awkwardness or redundancy.

D:  This answer choice incorrectly refers to the singular noun "Discussion" with the plural verb "have...focused". Further, Option D fails to maintain parallelism between "the possibility of Earth growing warmer" and "to what extent it might"; remember, any elements joined by a conjunction ("and" in this sentence) must be parallel.

E:  This answer choice fails to maintain parallelism between "whether Earth would grow warmer" and "the extent that is"; remember, any elements joined by a conjunction ("and" in this sentence) must be parallel. Further, Option E incorrectly uses the simple present tense verb "is" to refer to a hypothetical future event; remember, future actions are conveyed through the simple future tense, and the simple present tense is used to indicate actions taking place in the current time frame, indicate habitual actions, state universal truths, and convey information that is permanent in nature.

Hence, C is the best answer choice.

To understand the concept of "Simple Tenses" on GMAT, you may want to watch the following video (~2 minutes):

https://www.youtube.com/watch?v=ATNTtugB9fM

All the best!
Experts' Global Team

anupamadw · Answer

Experts please help to check.
A , D --- Discussion of X have --> SV error
E --- The discussion has focused on 1) whether Earth would grow warmer 2)the extent that is -->> ||sm issue
Between B and C
B-- has usually had as its focus VS discussion has focused ( Better)
Also in (C) whether Earth  would grow warmer  and to what extent (  would grow warmer ) --- complete idea
(B)whether Earth would get warmer and what the extent would be ( ???) -- looks like incomplete

So (C)

johng2016 · Answer

Official answer:

Reasoning: 
- The sentence contrasts climatologists' views concerning greenhouse effects with other views that emphasize global warming. 
- The main subject of the sentence is  discussion..... , which is singular, so the main verb should be singular.
- The two things that are said to be the focus of discussion should be in parallel form.

A. The plural verb  have...had  does not agree with the singular subject discussion. The phrases  the possibility... warmer  and  to what... might  are not parallel.

B. The verb form  has had as its focus  is unnecessarily wordy; the noun clauses are parallel in form, but it is not clear what the  extent  refers to

C.  CORRECT  This has correct Subject-Verb agreement, eliminates the wordiness of the original sentence, and the phrases  whether... warmer  and  to what extent  are parallel.

D. The singular subject discussion does not agree with the plural verb have focused.  The possibility of...  is not parallel with  to what extent...

E. The two phrases following  on  are not in parallel form. What  that  refers to in  the extent that is  is unclear.

stevekeating · Answer

B has “and what the extent would be”. C has “and to what extent”. B is unidiomatic, but notice it is also longer that C. The test makers prefer the simpler, shorter option whenever possible. If you are finding it difficult to decide between two options that sound good to you, it may be the safest option to choose the shorter one. “Until you will not get good marks” is incorrect. The correct expression is “until you get good marks”.

rishi02 · Answer

Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might, but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.

Subject = Discussion = Singular 
Hence need Singular verb

(A) Discussion of greenhouse effects  have  usually had as a focus the possibility of Earth growing warmer and to what extent it might,

(B) Discussion of greenhouse effects has usually had as its focus whether Earth would get warmer and what the  extent  would be,

Extent of what ?

(C) Discussion of greenhouse effects has usually focused on whether Earth would grow warmer and to what extent,

CORRECT

(D) The discussion of greenhouse effects  have  usually focused on the possibility of Earth getting warmer and to what extent it might,

(E) The discussion of greenhouse effects has usually focused on whether Earth would grow warmer and the  extent  that  is,

Usage of simple present tense is incorrect to denote an action in the future

zoezhuyan · Answer

Hi experts,

1/
(B) Discussion of greenhouse effects has usually had as its focus whether Earth would get warmer and what the extent would be,

as I know, the correct is focus on if focus works as a verb,
I wonder whether prep "on" should follow immediately if "focus" works as a noun, that's why I cross off B, but I am not sure whether the reason is valid, because OE does not mention it.

please conform,

2/
(C) Discussion of greenhouse effects has usually focused on whether Earth would grow warmer and to what extent,

for meaning : I don't think "...what the extend would be." is not clear,
it is similar to , 
...what the question is.
 for grammar :
I have not gotten why "whether ...." and "to what" are parallelisms?
"whether" cause is a question clause (I do not know the terminology)
"what" clause is a question clause as well.
"to what" clause is a prep phrase for me
IMO, whether can parallel to what,
here, the correct answer is  what clause  parallel to  to what clause
  (for me ,it is a prep phrase)

desiring your explanation

thanks a lot
have a nice day.
>_~

guenthermat · Answer

I don't understand why  whether Earth would grow warmer  is parallel to  to what extent :

>  whether Earth would grow warmer   is a dependant clause with a conjunction, a subject and a verb
>  to what extent  is is a prepositional phrase with a preposition and a noun

Moreover, the root  Discussion.... has focused on... 
a)  ...whether Earth would grow warmer   works 
b)  ...to what extent  doesn't work

Thus, I'd conclude that the the Earth part and the extent part aren't parallel.

Any explanations? Thank you!

mikemcgarry · Answer

Dear guenthermat , I'm happy to respond. :-)

First of all, remember that parallelism is NOT a grammatical structure. Parallelism is a logical structure, and any matching pattern in the grammar serves only to reflect the underlying logic. Thus, structures that don't appears similar can still be parallel if they are logical equivalents. The two items in parallel here are substantive clauses , a.k.a noun clauses. A substantive clause one kind of dependent clause, and it always takes a noun-role in a sentence (subject, direct object, object of preposition). Both of these clauses are acting as nouns and objects of the verb " depend on ." 1) whether Earth would grow warmer = a straightforward substantive clause 2) to what extent - this is tricky for a couple reasons. First of all, in the second branch of parallelism, a writer is always allowed to omit words that were present in the first branch. See: Dropping Common Words in Parallel on the GMAT This is always a confusing point for non-native speakers in particular. English is a difficult language and it's hard enough to understand all the words that are present, but now we also have to figure out the words that are missing!! With those repeated words, the full version would be: to what extent the Earth would grow warmer ] The entire sentence would be long and repetitive if all those words that appears in the first branch of the parallelism were repeated in the second. That's precisely why sophisticated writers, such as the author of this sentence, chose to drop repeated words: omitting the words creates sleeker, more elegant sentences. Also, and this is another tricky point: when a dependent clause (such as a substantive clause or a relative clause) begins as a preposition, it is as if the preposition is "inside" the clause. Thus, this second substantive clause is acting as a noun parallel to the first one, and while it appears inside a preposition, it is as if that preposition were inside of it. All of this is very sophisticated, but this is why (C) is 100% correct and why it contains flawlessly constructed parallelism. Does all this make sense? Mike :-)

Lucy Phuong · Answer

Dear expert @mikemcgarry,
I chose correct choice and eliminated wrong options in the same way as in previous posts. I just had a minor concern that is "grow warmer" similar, in meaning, to "get warmer"? If not and depending on particular context, then could you please show us more? Thank you a lot.

mikemcgarry · Answer

Dear Lucy, How are you? I'm happy to respond. :-)

Both options, " to get warmer " and " to grow warmer ," mean exactly the same thing. I would say that "t o get warmer " is more casual and colloquial, a little less typical of GMAT SC language, and " to grow warmer " is slightly more well-spoken and characteristic of that language. The choice between these two would NOT be a deciding split--we cannot say that " to get warmer " is definitively wrong. At the same time, it's not at all surprising that the OA employs the well-spoken option. There are some rules in grammar that, like math, are black/white, right vs. wrong. For example, SVA and pronoun rules have to be 100% correct. Other issues are particularly subtle, such as word choice or split infinitives or ending with a preposition--these would never deciding splits on the GMAT SC, but as a general rule, the less preferred pattern appears only in SC choices that are wrong for other reasons. Thus, familiarity with these issues can confirm our other choices. Does all this make sense? Mike :-)

daagh · Answer

Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,  but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.

(A) Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,

(B) Discussion of greenhouse effects has usually had as its focus whether Earth would get warmer and what the extent would be,

(C) Discussion of greenhouse effects has usually focused on whether Earth would grow warmer and to what extent,

(D) The discussion of greenhouse effects have usually focused on the possibility of Earth getting warmer and to what extent it might,

(E) The discussion of greenhouse effects has usually focused on whether Earth would grow warmer and the extent that is,

To whomever, it may suit ( especially the newly initiated))

I don't say it is a magic wand nor is it universally applicable; yet at times of doubt, while dealing with complex issues, you might be lucky to spot a few established customs to narrow down perhaps to almost the correct choice. After all, one percent wrong is 100 percent wrong in GMAT and we must be astute enough to spot those silly peccadilloes to eliminate a good chunk of incorrect choices. For example, in this given case, we can in one shot kick out choices A and D, for missing the number agreement. We might also dump B as per Verb -Adjective - Noun (VAN) rule. 
Between C and E, the use of the definite article 'the' to denote a broad, perpetual and usual discussion is erroneous as per established norms. E misleadingly suggests that we are referring to a particular discussion. Therefore, C is the most likely choice, even if you are not clear which is the more parallel between C and E.

Let me caution you again that this knack goes with the usual disclaimers.

ydmuley · Answer

Discussion of greenhouse effects have usually had as a focus the possibility of Earth growing warmer and to what extent it might,  but climatologists have indicated all along that precipitation, storminess, and temperature extremes are likely to have the greatest impact on people.

(A) Discussion of greenhouse effects  have  usually had as a focus the possibility of Earth growing warmer and to what extent  it might ,

(B) Discussion of greenhouse effects has usually had as its focus whether Earth would get warmer and  what the extent would be ,

(C) Discussion of greenhouse effects  has  usually focused on whether Earth would grow  warmer  and  to what extent ,

(D) The discussion of greenhouse effects  have  usually focused on the possibility of Earth getting warmer and to what extent   it might ,

(E) The discussion of greenhouse effects has usually focused on whether Earth would grow warmer and  the extent that is ,

Discussion is Singular and hence we need singular "had" + parallel structure "whether warmer" and "to what extent"

Hence - C

Saumya2403 · Answer

Please explain why choice C is correct

mikemcgarry · Answer

Dear Saumya2403 , I'm happy to respond. :-)

My friend, I am going to chide you. What you have asked here is a low quality question. Think about it: how much time and effort did you put into formulating your question? From the appearance, it looks as if you just typed it quickly and hit enter, with a minimum of engagement. I am sorry to tell you this, my friend, but you really are going to learn very little from this approach. You see, it's a misunderstanding of many students that education is something that teachers and test experts "do" to a student, and the student is simply the passive recipient. In fact, you are 100% responsible for every aspect of your education. Education is something you do to yourself, by yourself, and for yourself, and we teachers & test prep experts can only help you. Some of the biggest determinations of how much you ultimately will learn are your commitment and determination. Are you really showing up for yourself? Do you really believe in your own possibility of success? Are you willing to engage with tremendous effort in order to bring forth your best possibilities. If you want excellent results, you need to practice the habits of excellence. One of these is the habit of formulating excellent questions. See this blog article. Asking Excellent Questions Here's my challenge to you. Read that blog very carefully, and then come back her, study all the entries on this thread, and if you still don't understand why (C) is correct, formulate the highest quality question you can. If you do that, I will be more than happy to answer it. Remember, my friend: how you do anything is how you do everything. Does all this make sense? Mike :-)

yash321 · Answer

Could some please give a detailed explanation why option "b" is wrong, I am not able to understand.

egmat · Answer

Hello yash321 , I will be glad to help you out with this one.

Following are errors in Choice B: 1. Meaning Error: It is not very clear what the extent actually corresponds/refers to. extent usually corresponds to something to convey the complete meaning. (the extent of something). The extent of damage to buildings due to the earthquake is still unknown. (Correct) The earthquake damaged a lot of buildings, but the extent is unknown. (Incorrect) 2. Idiom Error: The current construction requires a noun to follow the word focus. Michael has usually maintained personal growth as his focus. (Correct) Michael has usually maintained as his focus personal growth. (Rephrase: Correct) Michael has usually maintained as his focus how to improve his personal growth. (Clause: Incorrect) Similarly, in this sentence, the usage of the clause whether Earth would get… after focus is grammatically incorrect. Hope this helps.

Thanks. Shraddha

naveeng15 · Answer

Reasoning:
- The sentence contrasts climatologists' views concerning greenhouse effects with other views that emphasize global warming.
- The main subject of the sentence is discussion....., which is singular, so the main verb should be singular.
- The two things that are said to be the focus of discussion should be in parallel form.

A. The plural verb have...had does not agree with the singular subject discussion. The phrases the possibility... warmer and to what... might are not parallel.

B. The verb form has had as its focus is unnecessarily wordy; the noun clauses are parallel in form, but it is not clear what the extent refers to

C. CORRECT This has correct Subject-Verb agreement, eliminates the wordiness of the original sentence, and the phrases whether... warmer and to what extent are parallel.

D. The singular subject discussion does not agree with the plural verb have focused. The possibility of... is not parallel with to what extent...

E. The two phrases following on are not in parallel form. What that refers to in the extent that is is unclear

Discussion of greenhouse effects have usually had as a focus the

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards

GMAT Sentence Correction (SC - EA only) Questions

Discussion of greenhouse effects have usually had as a focus the

Prep Toolkit

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards