GMAT Sentence Correction (SC) | Re: Providing initial evidence that airports are a large source

Providing initial evidence that airports are a larger source of pollution than they were once believed to be, environmentalists in Chicago report that the total amount of pollutant emitted annually by vehicles at O'Hare International Airport is twice as much as that which is being emitted annually by all motor vehicles in the Chicago metropolitan area.

(A) as much as that which is being emitted annually by all
(B) as much annually as is emitted by the
(C) as much compared to what is annually emitted
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