In a particular experiment, a researcher monitored plant growth in one group of plants by
varying the amount of sunlight the plants were exposed to. Another group of plants received
the same amount of sunlight each day. He found that the amount of sunlight had a direct
effect on plant growth.

In this experiment, the control is.

A. amount of sunlight

B.the group of plants that were exposed to different amounts of sunlight

C.the group of plants that received the same amount of light each day

D.plant growth

E.amount of fertilizer