Is a major factor in dictating how much energy the vehicle can absorb to protect the occupants.

The correct answer is speed. Physics play a major role here so remember that greater the mass and the speed of the vehicle the greater the force and bigger the energy. No car can protect you from every possible scenario and it is the speed that is maybe the biggest factor to your safety as it directly influences the amount the energy that the car can and will absorb.

Speed is the major factor that helps in determining the energy that is taken by the vehicle to help the occupants. Mass of the vehicle and the speed help us calculate the energy. The more those two factors will be the more will be the force and energy associated with the vehicle.

They must use the scientific method