carbon monoxide

[clock60]

between C and E how to chose

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.

[kvcpk]

IMO E.

" increased by enough of a percentage " in C is awkward.
It means that levels have increased by x percent of a percentage. Assuming that x percent is enough.

On the other hand, E looks concise

[clock60]

hi kvcpk
this sentence is driving me crasy.
the answer is not E ( i also pick up E)

[selango]

IMO C

What is increased?Carbon Monoxide Level.

Check option E

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough.This meaning is not concise.Also increased enough is awkward.

[clock60]

IMO C

What is increased?Carbon Monoxide Level.

Check option E

Levels of carbon monoxide in the atmosphere during the twentieth century increased enough.This meaning is not concise.Also increased enough is awkward.

hi selango
i am pretty weak in SC
so can you explain again what is the difference between
C) Levels of atmospheric carbon monoxide increased sufficiently and
E) Levels of carbon monoxide in the atmosphere .....increased enough

[kvcpk]

hi kvcpk
this sentence is driving me crasy.
the answer is not E ( i also pick up E)

Sorry, I read B instead of C.

I did not even look at the other options.. My bad!!

out of C and E, C looks good.
in E, Levels of carbon monoxide in the atmosphere is wordy when compared to C.
As Selango said, "increased enough" looks awkward.

[selango]

In option E,the meaning is not clear.

"During the twentieth century" modifies the carbon monoxide levels instead of describing when those levels "increased." This means that carbon monoxide levels "increased enough" later.