Question Bank: Carbon monoxide levels in the atmosphere grew

[RahulB226]

Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

A. Carbon monoxide levels in the atmosphere grew by enough of an increased percentage during the twentieth century that it began to trap heat radiating from the Earth, and it caused the average surface temperature to rise.

B. Carbon monoxide levels in the atmosphere increased by enough of a percentage during the twentieth century that they began to trap heat radiating from the Earth, causing the average surface temperature to rise.

C. Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.

D. Atmospheric carbon monoxide levels increased by a sufficient percentage during the twentieth century to begin trapping heat radiating from the Earth, which caused the average surface temperature to rise.

E. Levels of carbon monoxide in the atmosphere during the twentieth century increased enough to begin trapping heat radiating from the Earth, causing the average surface temperature to rise.Hide Explanation.

The correct answer is cited as C - however the phrase "to begin trapping heat radiation...." doesn't it indicate purpose? Levels of Carbon monoxide didn't increase to do some harm to earth by trapping heat, etc. they increased and as a result they began to trap heat. In my opinion the best choice is B despite having an incorrect phrase "by enough of a percentage".

I have two generic queries arising from this question: -

1. When does the usage of word 'to' indicate purpose and when it doesn't? Please cite examples.

2. The information presented in original answer can be ignored in what conditions, such as in this question the original sentence states that levels grew by an an increased percentage, ignoring the redundancy due to grew and increase the fact that the levels increased by 'one' percentage point could be a vital information which the third choice C (correct answer) misses. In which scenarios, is it considered okay to skip the information from the original sentences in the answer choices.

[RonPurewal]

1/
"sufficient(ly) + to + verb" is an idiom.

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2/
the "original" meaning has NO inherent importance.
the only meaningful distinction is "reasonable/intended meaning" versus "unreasonable/absurd/nonsense meaning". the INTENDED meaning should ALWAYS be clear—even if the original sentence is incorrectly written.

in other words—it never matters which option is "choice A". if you switch "choice A" with one of the other choices, the answer to the problem should NEVER change.
(if "original meaning" were relevant, then the answer might change depending on which choice is labeled as "the original").

[RahulB226]

Quote -
in other words—it never matters which option is "choice A". if you switch "choice A" with one of the other choices, the answer to the problem should NEVER change.
(if "original meaning" were relevant, then the answer might change depending on which choice is labeled as "the original").
Unquote

Just to confirm, you mean that even if we change the original exact meaning of the 'original sentence', which would always be repeated in "choice A", and retain the intended meaning of the sentence by going with any other choice which is grammatically correct and concise then also we are good to go?

On a different note, on official GMAT mocks my CR and RC score is above 40 but my SC score of sub 40 levels is bringing my overall verbal score down to sub 40 levels. I have completed MGMAT SC guide and EGMAT SC course. I had completed the foundation verbal from MGMAT and Aristotle SC foundation chapter to solidify my foundation before I tried the SC guide and EGMAT SC. I am a non-native speaker.
Is there any advice which you can give working on which can help me get better at SC?

[cyy12345]

Hello Ron and other MGMAT moderators,

May I ask you two questions regarding to the bold sections (which I annotated) in the answer C?

C. Levels of atmospheric carbon monoxide increased sufficiently during the twentieth century to begin trapping heat radiating from the Earth, causing the average surface temperature to rise

Question 1: "to begin trapping heat..."
How can the levels of atmospheric carbon monoxide to begin trapping heat? I mean, how can a level, which is a number or some other type of measurement, perform this action?

Question 2: "causing the average.."
What is this "comma ing" modifier modifying? I think it is modifying the subject of the main clause; in this case, it is "levels of atmospheric carbon monoxide". But if so, we are back to question 1: how can the levels of something execute such action?

Thanks a lot in advance!

[RonPurewal]

Question 1: "to begin trapping heat..."
How can the levels of atmospheric carbon monoxide to begin trapping heat? I mean, how can a level, which is a number or some other type of measurement, perform this action?

this is a non-issue in the problem at hand, since all 5 choices contain "levels of carbon monoxide" or "carbon monoxide levels".

sometimes, small compromises are made in writing these kinds of sentences, so that the author doesn't have to use an absolutely ridiculous number of words for the sake of "precision".
for instance, you've probably seen sentences like
The revenue office sent out more than 100,000 tax-return packets yesterday.
...obviously an office can't literally sent out mailings, but this is the only way to write the sentence without using a HUGE number of unnecessary words.

the same thing is going on here -- WHICH IS WHY THIS ISN'T TESTED IN THE PROBLEM.
do NOT focus on non-issues!
if you study things that aren't tested, you'll get WORSE at this exam!

[RonPurewal]

Question 2: "causing the average.."
What is this "comma ing" modifier modifying? I think it is modifying the subject of the main clause; in this case, it is "levels of atmospheric carbon monoxide". But if so, we are back to question 1: how can the levels of something execute such action?

Thanks a lot in advance!

this modifier -- like all other "comma + __ing" modifiers -- describes the ACTION that precedes it.
comma + __ing modifiers DO NOT just describe nouns/subjects.
remember, that's actually the entire point of the "comma __ing" modifier -- to describe ACTIONS specifically, not just their subjects or other nouns.

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here, it's the ACTION of trapping heat radiating from the Earth that causes temperatures to go up -- an interpretation that, of course, makes perfect sense.