B, while the lights consume electricity and light, that is, the conversion of electrical energy into light energy,
C, "overhead" small fan can be converted into light.
C, "head" of the small fan can be converted into electricity, so long as there is wind, this street lamp can also generate electricity, to fill a little cloudy days and nights can not generate electricity blank, is conducive to the street lamps at night lighting use;
D, the battery in the night when the discharge, the chemical energy into electrical energy;
So clear "wind and light Complementary" landscape energy-saving lamps after each part of the function, you can know C option is correct.
So choose C.