3. In this example, age is:
a. The independent variable (IV).Explanation:Age is the independent variable as it is a cause for a change. Here the researcher is measuring the impact of age on running speed.4. In this example, the time it takes to complete the race is:
c. The dependent variable (DV).Explanation: Time is dependent on age, which means that time depends on age. As the age of the participant increases, the running time decreases. Hence, time is a dependent variable.5. In this example height is:
c. A confound variable.Explanation:Height is considered as a confounding variable because it might also be the reason for teenagers running faster. The researcher cannot control the height of the participants, which makes it difficult to determine whether the height or age is the reason behind faster running. A confounding variable is an external variable that affects the relationship between independent and dependent variables.