Final answer:
The dependent variable in a study examining the effect of stress on heart rate in humans is the heart rate. option b
Step-by-step explanation:
When studying how stress affects the heart rate in humans, the dependent variable in this study would be the heart rate. The dependent variable is the response that is measured in an experiment, and it is the outcome that may change due to manipulation of the independent variable, which in this case is stress. Concepts such as cardiac output, how exercise affects heart rate, and the regulation of heart function by cardiovascular centers and cardiac reflexes are related to the understanding of how these variables interact. When studying how stress affects the heart rate in humans, the dependent variable in this study would be the heart rate.