Diesel engines burn as much as 30% less fuel than gasoline engines of comparable size, as well as emitting far less carbon dioxide gas and far fewer of the other gasses that have been implicated in global warming.

(A) of comparable size, as well as emitting far less carbon dioxide gas and far fewer of the other gasses that have Correct answer and no apparent errors.

(B) of comparable size, as well as emit far less carbon dioxide gas and far fewer of the other gasses having "having been" must be used to denote an action that has happened before another action. Incorrect usage here. Eliminate.

(C) of comparable size, and also they emit far fewer carbon dioxide and other gasses that have "and also" and "they" are redundant. Also, "far fewer carbon dioxide" is incorrect - need to use "lesser" for an uncountable. Eliminate.

(D) that have a comparable size, and also they emit far fewer of the other gasses having Omits to mention "carbon dioxide". "and also" and "they" are redundant. "having been" must be used to denote an action that has happened before another action. Incorrect usage here. Eliminate.

(E) that have a comparable size, as well as emitting far fewer of the other gasses having Omits to mention "carbon dioxide". Also, "having been" must be used to denote an action that has happened before another action. Incorrect usage here. Eliminate.

Hope this helps.
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Answer A.

"Having been implicated" is just wrong so BDE are out.

Between A and C, we must use less and fewer to differentiate between amount of CO2 and number of gasses. So C is out.

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