Sentence Correction

Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chloroflurocarbons (CFC's).

A) acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate
B)acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating
C)act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating
D)they act as a global thermostat that thus keeps the Earth either from burning up or freezing over, even though it also accelerates
E)they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate


SPOILER BELOW




The answer is A. However, my question is, isn't the phrase acting as global thermostat and thus keeping Earth from either burning up or freezing over a modifier? If so, then it is incorrectly placed as it should modify "ice particles", whereas as it is written above, it seems to be modifying "solar radiation".

Can anyone please comment?

Question is not sourced from official GMAT materials so it could be a dud question.

acting as a global thermostat is a modifier for 'reflect and absorb solar radiation'
right idiom is - from either X or Y

Leonard C wrote:Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiation, acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate the destruction of the ozone layer by reacting with chloroflurocarbons (CFC's).

A) acting as global thermostat and thus keeping Earth from either burning up or freezing over, they also accelerate
B)acting as a global thermostat and thus keeping Earth either from burning up or freezing over, while also accelerating
C)act as a global thermostat and thus keep Earth from either burning up or freezing over, while also accelerating
D)they act as a global thermostat that thus keeps the Earth either from burning up or freezing over, even though it also accelerates
E)they act as a global thermostat to thus keep Earth from either burning up or freezing over, but they also accelerate


SPOILER BELOW




The answer is A. However, my question is, isn't the phrase acting as global thermostat and thus keeping Earth from either burning up or freezing over a modifier? If so, then it is incorrectly placed as it should modify "ice particles", whereas as it is written above, it seems to be modifying "solar radiation".

It is modifying ice particles.
had there been any which / that after "solar radiation" thn it would have modified that.

Read this
Although ice particles in the upper atmosphere benefit Earth in that they reflect and absorb solar radiations, which are harmful......

now you see it clearly refers to radiations

Can anyone please comment?

Question is not sourced from official GMAT materials so it could be a dud question.

I think the answer is A.

Here's my explanation:

To simplify, the sentence is saying that ice particles benefit Earth but also destruct. It is inaccurate to say that ice particles benefit Earth WHILE destructing it.- eliminate B, C

"they reflect and absorb solar radiation, acting as global thermostat and thus keeping Earth from either burning up or freezing over" --> that is in the middle describes the Earth - eliminate D, E

You can also eliminate E since "although" comes in the beginning of the sentence, it is not necessary to add "but" before "they also"

Left with choice A.

i thought B was the answer, between A and B.

SYim

I don't agree with your explanation for B. In reality, that is exactly what is happening, concurrent benefit and destruction.

Anonymous wrote:i'd also question the source of this question.

this question is from the gmatPrep

There must be a typo in A (it should say "acting as _a_ global thermostat") but aside from that, A is clearly the superior choice.

If I understand your question, you're wondering how it can be that this modifier can be separated from the phrase "ice particles" and yet be considered to be correctly placed. The reason it's OK is that -ing modifiers that describe actions that take place at the same time as the main clause action don't follow the same rule as modifiers with 'which' -- they don't have to be adjacent to the noun that describes the thing that's doing the action.

In other words, if I said, "He walked on down the street, which surprised me" that would be wrong, because 'which' would have to be interpreted as meaning that the _street_ surprised me. But if I said, "He walked on down the street, whistling a happy tune," it's fine, because 'whistling a happy tune' is a modifier describing an action that takes place along with the main clause action, and modifiers of this type can just follow the main clause without any problems (and it doesn't mean that the street was whistling a happy tune).

Does that help or were you asking about something else?

I have one doubt i would appreciate if you can throw some light on it

Here is my understanding of modifiers:

1. i went to the place ,which was hot.
Here clearly which refers to place.

Rule: which refers to the preceding noun.

2. He was playing the game, slowly and neatly.

slowly and neatly adverbial modifiers refering to playing.

Rule: Adverbial modifiers need not be closed to the verb

3. Participle modifiers:
-ing-
He walked on down the street, whistling a happy tune.

here whistling refers to He.
Rule: ing participle refers to the subject of the preceding clause

-ed
Rule for -ed participle is that it refers to the immediate preceding noun.


Karen pls correct me if i am wrong....

I concur with Karen on modifier. That leaves us with option A and B. Option B failed on two aspects: Idiom (Although X, Y) and Parallelism (they reflect and absorb..., they also accelerate..).

I markes it as B

because they also accelerates......i thought was ambiguous and also not parallel to acting.

Hence I chose B.

Can anyone please explain my mistake?