Concept:Friction always opposes relative motion between two surfaces in contact.Explanation:When the brakes are applied, the tyres experience a frictional force from the road.This frictional force acts in the opposite direction to the motion of the car.Because it opposes motion, it slows the car down.Slowing the car is the desired effect of braking, so this friction is advantageous.Answer:D. an advantage because it is in the opposite direction of the motion of the car.