Algebra-1

Question Analysis
This question tests the student's ability to identify the independent variable in a study involving multiple categories. The independent variable is the one that is manipulated or controlled by the researcher.

Key Concept Explanation
In this context, the independent variable (type of exercise) is the factor that the researcher can control and change to observe its effect on the dependent variable (heart rate). The types of exercise (running, cycling, swimming) are the different levels of the independent variable.

Step-by-step Solution
1. Identify the variable that is being manipulated or controlled: The type of exercise (running, cycl...