GMAT Sentence Correction (SC) | Re: Diesel engines burn as much as 30 percent less fuel

Diesel engines burn as much as 30 percent less fuelas gasoline engines with comparable size do, and they emit far less carbon dioxide and other greenhouse gases, which have been determined to be contributing to global warming.

A) as gasoline engines with comparable size do, and they emit far less carbon dioxide and other greenhouse gases, which have been determined to be contributing
B) as gasoline engines of comparable size do, emitting far less carbon dioxide and other greenhouse gases, which