Final answer:
In the dimpled car experiment, the independent variable is B. Dimples on the car, as the experiment aims to examine how the dimples affect car performance.
Step-by-step explanation:
In the dimpled car experiment, the independent variable is the factor that is changed or controlled by the researchers to examine its effect on the dependent variable. The dependent variable is the outcome that is measured in the experiment. According to the scenario provided, the independent variable is B. Dimples on the car. This is because the experiment seeks to understand how the presence or variation in dimples on the car's surface affects its performance, such as its speed, while keeping other factors like the type of car consistent.