Question

marcus is testing how altitude affects heart rate during exercise. which variable is the dependent variable?
altitude, because it is manipulated by marcus
altitude, because it is measured by marcus
heart rate, because it is manipulated by marcus
heart rate, because it is measured by marcus

Explanation:

A dependent variable is the one that is being measured and is affected by the independent variable. Here, heart - rate is being measured and is affected by altitude. Altitude is the independent variable that Marcus manipulates.

Answer:

D. Heart rate, because it is measured by Marcus