Rhonda conducted a study in which she has tested the effectiveness of the drug DHEA on improving episodic memory in older adults. She tested her subjects on two different occasions; in one session her subject received a placebo, and second they received 50 mg of DHEA. At each test session the subjects completed a recognition memory task to measure episodic memory performance. What is Rhonda's dependent variable?

Drug dosage (50 mg DHEA vs. placebo)
Participant age
Episodic memory
Performance on the recognition memory task