A Researcher Is Interested in the Effect of Exercise on Stamina

Multiple Choice

A researcher is interested in the effect of exercise on stamina in elderly patients.The patients are randomly assigned to be in a high-exercise or low-exercise training program for 8 weeks.At the end of the program,their stamina is measured by seeing how long they can walk comfortably on a treadmill.In this study,the dependent variable is

A) number of minutes on the treadmill.
B) the exercise program (high versus low) .
C) heart rate during the exercise program.
D) the 8-week duration of the exercise program.