Dr McGlynn Is Conducting a Study on Reaction Time

Multiple Choice

Dr. McGlynn is conducting a study on reaction time. He allows subjects to exercise strenuously for either 0, 10, or 20 minutes. Next, subjects are seated at a table containing a red push button and a yellow light. Each subject is asked to push the button as soon as he or she sees the light flash. Dr. McGlynn measures the time it takes each subject to push the button after the light is lit. What is the independent variable in this study?

A) exercise
B) the amount of time spent exercising
C) the button
D) the light
E) reaction time