Final answer:
The correct answer is b) Independent variable: Time spent running; Dependent variable: Heart rate, as the time spent exercising is manipulated and the heart rate is the expected outcome.
Step-by-step explanation:
In scientific research and experiments, we deal with independent and dependent variables. The independent variable is the one that is controlled or manipulated, whereas the dependent variable is the one that is measured and is expected to change as a result of the manipulation of the independent variable. In the scenario given, the hypothesis is: 'If a person runs in place for 10 minutes then their heart rate will increase because blood needs to reach their muscles faster.' Therefore, the independent variable, which is the one we control, is the time spent running. The dependent variable, which we expect to change or measure, is the heart rate. Hence, the correct answer is b) Independent variable: Time spent running; Dependent variable: Heart rate.