GMAT Critical Reasoning (CR) | Re: If all the cars in the US were powered by electric motors

If all the cars in the US were powered by electric motors
instead of Gasoline engines, without any reduction in the number of
miles driven annually, then the total amount of fossil fuels consumed
in the US would be cut in half, despite the fact that most of the
electricity in the US is produced by burning the fossil fuels.
If the statement concerning the impact of electric cars on the
consumption of fossil fuels is true, which of the following
statements must be true?

a. Coal, natural gas, and