An experimenter tests the hypothesis that physical exercise improves mood. Subjects in the experimental group exercise Mondays, Wednesdays, and Fridays and both those in the experimental and those in the control group have their mood tested on Tuesdays and Thursdays. What is the independent variable?

the exercise  

Explanation:

         In an experiment, an independent variable are those variable which can be controlled and changed to alter the results of the experiment. The changes in the independent variable are seen in the depended variables.

        Where as a dependent variable are those which are depended on the independent variables and can be measured by the experimenter.

        In the context, an experimenter wanted to test a hypothesis and for this the test subjects are allowed to exercise on three days in the week and their mood is tested on the day after they exercise. In this experiment, the independent variable is the exercise the test subject do as the experimenter can change or manipulate the exercise.

answer; i believe its (transgender);