Consider Newton's 2nd Law ∑F=ma (the net force on an object is the object's mass times its acceleration).

If a car is moving to the left with constant velocity, one can conclude that

a) there must be no forces applied to the car.

b) the net force applied to the car is directed to the left.

c) the net force applied to the car is zero.

d) there is exactly one force applied to the car.