The answer would be A) Photovoltaic cell.
Reason:
B) turbine, would convert either air or water into electricity through mechanical energy.
C) battery, would just store chemical energy that later is released in whatever you put it in.
D)Copper Tubing, does not make sense. It channels energy but doesn't generate or store it in any way.
***Photovoltaic comes from the Greek word photo- meaning light. This alone should be a good hint.