A student conducts an experiment to test how music affects plant growth. In the experiment, she uses two identical plant seedlings. One plant is exposed to classical music. The other plant is exposed to no music. She measures and compares the different plants' height each week, for two months of time.

What is the independent variable in this experiment?

A. two months of time
B. height of the plants
C. type of plant seedlings
D. exposure to music

D. exposure to music

Explanation:

Now, lets review what independent variable means. Independent variable: "The independent variable is the variable the experimenter changes or controls and is assumed to have a direct effect on the dependent variable. In an experiment, the researcher is looking for the possible effect on the dependent variable that might be caused by changing the independent variable." The student is able to control the music exposure, therefore making D your best bet.