Answer:
C. equal to the force of friction exerted upon the car.
Step-by-step explanation:
We know according to Newton's First Law Of Motion , an object in rest or in uniform motion will be in same state unless or until an external force is not provided.
In other words , When no force apply on the body it being in the state of uniform motion or in rest.
In the case given, the car is travelling in the highway at a constant velocity. Therefore net force acting on car in horizontal direction is equal to zero.
It means all the forces acting on horizontal direction cancelling each other which cause net force equals to zero.
Here, to cancel force of friction the force that pushes the car in forward direction must be equals to it.
Therefore, C. option is correct.