Question

how does adding cardio to one’s daily schedule affect their heart rate? the heart rate is the...
dependent variable
independent variable

Explanation:

In an experiment, the dependent variable is the one that is measured or affected by the independent variable. Here, we are looking at how adding cardio (independent variable, as it's the factor we manipulate) affects heart rate. So heart rate depends on whether cardio is added, making it the dependent variable.

Answer:

dependent variable