Physics

Newton's third law states that for every action, there is an equal and opposite reaction. The action and reaction forces act on different objects.

In the horse - cart system: The action force is the force exerted by the horse on the cart, pulling it forward. The reaction force (the equal and opposite force) is the force of the cart pulling backward on the horse.

Option A

The force of friction between the cart wheels and the road is a separate force that affects the motion of the cart.