For the first question about the car moving at constant velocity along a level road:
The correct answer is: c - zero.
When the car is moving at a constant velocity, it is in equilibrium with no net force acting on it. The forces acting on the car (such as friction and the driving force) are balanced.
For the second question regarding the effects of a nonzero net force on an object:
The correct answer is: b - being accelerated.
If a net force is acting on an object, it indicates that the object is experiencing a change in motion, which means it is being accelerated according to Newton's second law of motion (F = ma).