James took two pea plants, placing one in a dark closet and the other on a sunny window sill. Both are located in air-conditioned rooms. He then measured the growth of the pea plants after a week. In this experiment, sunlight is a(n)____________.
Aindependent variable
Bdependent variable
Cconstant
Dcontrol
Aindependent variable
Bdependent variable
Cconstant
Dcontrol