The main idea is to save energy and reduce pollution.And we need to evaluate if the increased usage of ethanol as a primary fuel source in conjunction with or in place of gasoline.

(A) Whether the energy required to grow and process the corn used as fuel is greater than the amount of energy ultimately produced.
Incorrect.The idea is to save energy.So, We need to evaluate the energy IN and energy out.
(B) Whether more energy is saved when using ethanol in conjunction with or in place of gasoline.
Correct.This statement is the repetition of the argument itself.
(C) Whether ethanol is as efficient a fuel as gasoline
Incorrect.It is mentioned that Ethanol is a cleaner fuel.
Lets Assume , Ethanol produce 50 % less pollution than gasoline.
But if it is only 10 % as efficient as gasoline, so the amount of ethanol burnt will be 10 times more than gasoline and it will produce more pollution in total.
In order to evaluate the argument , we need to know the efficiency
(D) Whether it is possible to produce more ethanol than is currently produced
Incorrect. Since, Argument advocates the increased usage of ethanol.We need to see if the production can be increased to meet the demands.
(E) Whether the process of growing corn for fuel would result in as much pollution as does the production of conventional gasoline
Incorrect.The idea is to reduce pollution.So, We need to evaluate the pollution produced by both the fuels.