Sentence Correction

In an effort to reduce the number of fires started by cigarettes, a major tobacco company is test-marketing a cigarette in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing the rate at which it burns and lowering the heat it generates.
A. in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing
B. in which they use thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows
C. that uses thin layers of extra paper to decrease the amount of oxygen when it enters the cigarette, thereby slowing
D. for which thin layers of extra paper are used to decrease the amount of oxygen that enters the cigarette, and thereby slowing
E. using thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows

[spoiler]Is 'that enters' in D part of parallel things in the whole sentence ?[/spoiler]

sam2304 wrote:In an effort to reduce the number of fires started by cigarettes, a major tobacco company is test-marketing a cigarette in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing the rate at which it burns and lowering the heat it generates.
A. in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing
B. in which they use thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows
C. that uses thin layers of extra paper to decrease the amount of oxygen when it enters the cigarette, thereby slowing
D. for which thin layers of extra paper are used to decrease the amount of oxygen that enters the cigarette, and thereby slowing
E. using thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows

[spoiler]Is 'that enters' in D part of parallel things in the whole sentence ?[/spoiler]

IMO: A

sam2304 wrote:In an effort to reduce the number of fires started by cigarettes, a major tobacco company is test-marketing a cigarette in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing the rate at which it burns and lowering the heat it generates.
A. in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing
B. in which they use thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows
C. that uses thin layers of extra paper to decrease the amount of oxygen when it enters the cigarette, thereby slowing
D. for which thin layers of extra paper are used to decrease the amount of oxygen that enters the cigarette, and thereby slowing
E. using thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows

Non-underline part gives good clues:" slowing the rate at which it burns and lowering the heat it generates. LOWERING suggests we need SLOWING. Drop B/E

C - has couple of key issues
1) USES signifies that somehow CIGARATTE is using thin layers on its own (can it happen?); we need some external agent to play that role; therefore passive sentence may be better
2) WHEN IT ENTERS vs ENTERING (in A) - signifies when oxygen wants to enter than only extra layer will decrease
3) IT has many referent

D - lets see some of the issues:
1) activity of ENTERS and SLOWING are parallel activities connected by AND...and therefore they should be in the same form
2) subject of ENTERS could be either OXYGEN or AMOUNT OF OXYGEN - we can only say 2nd is not correct, but the sentence structure is giving rise to such ambiguity (note, THAT ENTERS is not part of parallel element)
3) FOR WHICH

IMO A

+1 A

OA: A
parallel

Thanks for the information really its good to know that someone is thinking about people and environment.

Here is my Analysis:

In an effort to reduce the number of fires started by cigarettes, a major tobacco company is test-marketing a cigarette in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing the rate at which it burns and lowering the heat it generates.
A. in which thin layers of extra paper are used to decrease the amount of oxygen entering the cigarette, thereby slowing

This one sounds good. Let's keep it for now.

B. in which they use thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows

Use of "They" is wrong because Tobacco company is a singular unit. Also, Use of "Which" is wrong because it is referring to Cigarette.

C. that uses thin layers of extra paper to decrease the amount of oxygen when it enters the cigarette, thereby slowing

When should refer to places/period. Here, it refers to oxygen -- wrong.

D. for which thin layers of extra paper are used to decrease the amount of oxygen that enters the cigarette, and thereby slowing

The usage of for which is wrong. "For" can sometimes be used instead of because. so, the sentence becomes nonsensical.

E. using thin layers of extra paper in decreasing the amount of oxygen entering the cigarette, which slows

Use of "which" is wrong because it infers to cigarette. Its not the cigarette that slows the rate at which it burns... -- nonsensical