Ethanol Is a Renewable Chemical Energy Source,but There Are Presently

Ethanol is a renewable chemical energy source,but there are presently some barriers to its use as the primary fuel for cars.Which of the following is NOT among these barriers?

A) It is more expensive than gasoline.
B) It has a lower fuel value than gasoline.
C) Much of the energy it can produce is expended in its production.
D) It is a greater contributor to global warming than gasoline because it produces more carbon dioxide per carbon atom than gasoline.
E) All of the above are barriers to its use as a primary fuel.