Sentence Correction

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,torminess,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 dscussion of greenhouse effects have usually focused on the possibility of Earth getting warmer and to what extent it might,
E..The dscussion of greenhouse effects has usually focused on whether Earth would grow warmer and the extent that is,
I have understand the parallelism，but I am confused the to in Choice C. Someone can explain it?
Thanks in advance![/i]

I explain this SC here:
https://www.beatthegmat.com/2016-og-sc-23-t289349.html.

to what extent is an IDIOM that means how much.
to what extent the earth has grown = how much the earth has grown.

An idiom is a FIXED EXPRESSION.
The words in an idiom do not function as words with individual meanings but as a GROUP.
For this reason, do not attempt to analyze the purpose of an individual word in an idiom (such as the purpose of to in to what extent).
Instead, focus on how the idiom functions AS A WHOLE.

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 [Earth would grow warmer]).

(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 [Earth would grow warmer]" 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!


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