ankur.agrawal wrote: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.

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.

grew and increased are redundant.
, and - a seperator of IC, the second part of and has no subject.

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.
Contender.
The only thing that is stopping me from choosing this as answer is the referrant of they which is carbon monoxide levels. Since, logically CO levels cannot trap heat. I am confused.

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.

This gives me an idea that levels have purposely increased to trap heat radiation whereas due to the increase level the heat is trapped. Thus NO.

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.

Same as C.

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.

Contender.
Cause is increase and effect is trapping.
COMMA + verbing -> modifies preceeding noun or noun phrase 'trapping heat radiating from the Earth'.

AIM GMAT wrote: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.

The above option B , is wrong because of some awkward wordings and it states that the levels are causing the rise in temperature .

I too went for E , but experts say that the meaning inferrred from E is also wrong , the same issue that levels are not increasing the temp but CO .

I am not clear with the diffrence in Option C and E .Lets see what other members have to say on this .

ankur.agrawal wrote: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.

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.

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.

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.

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.

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.

GMATGuruNY wrote:

ankur.agrawal wrote: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.

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.

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.

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.

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.

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.

In A, it (singular) doesn't agree with levels (plural). Eliiminate A.

In B, enough....that they began is unidiomatic. Also, enough of a percentage feels redundant. A better wording might be a sufficiently high percentage. Eliminate B.

In D, which incorrectly refers to Earth. Eliminate D.

In E, it is unclear whether during the twentieth century is an adjective modifying the atmosphere or an adverb modifying increased. It must be clear what a modifier is modifying. Eliminate E.

The correct answer is C.

GMATGuruNY wrote:

ankur.agrawal wrote: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.

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.

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.

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.

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.

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.

In A, it (singular) doesn't agree with levels (plural). Eliiminate A.

In B, enough....that they began is unidiomatic. Also, enough of a percentage feels redundant. A better wording might be a sufficiently high percentage. Eliminate B.

In D, which incorrectly refers to Earth. Eliminate D.

In E, it is unclear whether during the twentieth century is an adjective modifying the atmosphere or an adverb modifying increased. It must be clear what a modifier is modifying. Eliminate E.

The correct answer is C.