Final answer:
The dependent variable is the distance it takes to stop the motor vehicle, while the independent variable is the speed at which the vehicle is traveling.
Step-by-step explanation:
The correct definitions for the terms 'dependent variable' and 'independent variable' in the given context would be:
Dependent variable: The distance it takes to stop the motor vehicle.
Independent variable: The speed at which the vehicle is traveling.
This is because the dependent variable is the variable that is being measured and plotted along the y-axis, while the independent variable is the variable that causes the dependent variable to change and is usually plotted along the x-axis.