Over the last five years, technological improvements have significantly reduced the cost of manufacturing and operating electric-powered cars. Nevertheless, the cost per gallon of gasoline at which it would become more economical to operate an electric car than a regular gas-powered car has remained unchanged.

Which of the following, if true, would do the most to explain why electric cars have become cheaper to operate but break-even point between electric and gas cars has not changed?

A) The price per gallon of gasoline has dropped by 25% over the last five years.
B) Electric-car manufacturers have managed to reduce production costs despite an increase in some raw material prices.
C) Improvements in aerodynamics have made regular gas-powered cars more efficient to operate.
D) Relative to the number of gas-powered cars, there are very few electric cars on the road today.
E) When the price of gasoline rises, more people are willing to take public transportation to work.

My Ques: what is the OA?