A scientist set up an experimental ecosystem in a sealed room with no windows. The experimental ecosystem has plants, and animals that eat those plants. The scientist can control whether the room is light or dark with a light switch outside the room.

The amount of carbon in the air of the ecosystem started out low. Then the amount of carbon in the air started to increase. Is the increase because the scientist switched the light on or because she switched the light off? What happened to the number of energy storage molecules in the living things?

The scientist . . .

a

switched the light off, and the number of energy storage molecules in the living things decreased.

b

switched the light off, and the number of energy storage molecules in the living things increased.

c

switched the light on, and the number of energy storage molecules in the living things increased.

d

switched the light on, and the number of energy storage molecules in the living things decreased.