Answer:
C.inertia
Step-by-step explanation:
Inertia is a property of matter to maintain its state of motion.
In this case, if the car was moving along with the people in it when the car stopped, the inertia of the people will cause them to continue moving.
This is why in a crash a person can be shot from the car, due to the inertia he has from his previous state of motion.
The complete sentence is: Unrestrained occupants of a car keep moving during the time the car takes to stop due to inertia. (option C)