(a). humans.
(b). an object.
(c). gasoline.
(d). tulip bulb.
(e). to move people.
(f). light bulb.
(g). microscope.
(h). cactuses.

Fact 1: Alight bulb requires electrical energy to produce light. Fact 2: Electrical energy is also energy. Given the two facts above, what requires energy to produce light?
Answer:
(f).