Newton's 2nd law of motion says:
Net force = (mass) · (acceleration) .
Newton didn't make up this law for his health.
Let's use it to answer this question about the car moving down the road.
Net force on the car = (car's mass) · (car's acceleration).
But the net force on the car is zero. So we can write:
0 = (car's mass) · (car's acceleration).
Look at the right side of this equation.
Newton's law tells us that the product of the car's mass and the car's acceleration is zero.
That tells us that at least one of three things must be true.
Either 1). the car's mass is zero, or 2). the car's acceleration is zero, or 3). Newton was crazy.
We're pretty sure that 1). and 3). are false. The car's acceleration is zero.
What does this mean ? It means that the car's speed and direction are not changing.
That's exactly what Choice-B says.