Although Photovoltaic Electricity Is Considered a "Clean" Power Source,one Issue

Multiple Choice

Although photovoltaic electricity is considered a "clean" power source,one issue with this electricity is that it __________________

A) will be replaced shortly with other sources of power for homes
B) is less efficient than fossil fuels
C) cannot be stored easily in large quantities
D) is not sufficiently understood
E) is dangerous if stored too long