Solar Thermal Energy Systems Are Inherently More Efficient Than Other

Solar thermal energy systems are inherently more efficient than other solar technologies because:

A) the technology involved is less expensive.
B) they can work at night and on cloudy days, as well as in full sunlight.
C) they concentrate the sun's energy.
D) they are dependent on circulating hot water.
E) the technology involved is less expensive and they can work at night and on cloudy days, as well as in full sunlight