imskpwr 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.

I will go with option C

ankit0411 wrote:

imskpwr 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.

I will go with option C

waiting for an expert to reply.

imskpwr 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.

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.("it" isn't right here."it" doesn't have any antecedent and doesn't fit in this context)

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.(they refer to CO levels,but the levels didn't trap heat,CO did.)eliminate this choice.

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.(which refers to earth) eliminate it

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.(this sentence states that levels of CO in 20th century increased lateron, may be in 21st century,and caused the trapping of heat.)it shifts the meaning and thus is incorrect.

(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.

"It" has no antecedent. "it" can't refer back to "carbon monoxide" (co), as CO is acting as an adjective here.

(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.

"they" has no antecedent. "they" can't refer back to "carbon monoxide" (co), as CO is acting as an adjective here.

(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.

Modified beginning with "which" refers to "Earth". Hence incorrect

(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.

I think (C) and (E) are both grammatically correct.

Examining from the meaning's perspective. (C) is better than (E).

Reason - (E) means that "Level of CO" of "20th Century" increased - Not sure when it increased
(C) means that "Level of CO increased" in "20th Century"
(C) appears much better than (E).

Mission2012 wrote:(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.

"It" has no antecedent. "it" can't refer back to "carbon monoxide" (co), as CO is acting as an adjective here.

(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.

"they" has no antecedent. "they" can't refer back to "carbon monoxide" (co), as CO is acting as an adjective here.

(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.

Modified beginning with "which" refers to "Earth". Hence incorrect

(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.

I think (C) and (E) are both grammatically correct.

Examining from the meaning's perspective. (C) is better than (E).

Reason - (E) means that "Level of CO" of "20th Century" increased - Not sure when it increased
(C) means that "Level of CO increased" in "20th Century"
(C) appears much better than (E).

The contest was between C and E.
The reasons given are not full-proof to eliminate a choice.
Still need an expert's opinion on the subject matter at hand.

imskpwr 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 E, it is not crystal clear what is being modified by during the twentieth century. Check my post here:

https://www.beatthegmat.com/mgmat-sc-t82409.html

GMATGuruNY wrote:

imskpwr 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 E, it is not crystal clear what is being modified by during the twentieth century. Check my post here:

https://www.beatthegmat.com/mgmat-sc-t82409.html

Thanks!
Not more. Not less. Just what is required. Excellent explanation once again.

Hi GMATGuruNY,

In option A and B, is Carbon Monoxide acting as an adjective?
If it is acting as adjective then can "it" and "they" refer back to them?

Thanks