Due to which force does a horse pulling a cart move forward?

The horse pulling a cart moves forward due to the force applied by the horse on the cart. When the horse exerts force on the cart through its muscles, an equal and opposite reaction force acts on the horse, causing it to move forward according to Newton’s third law of motion. This force is transmitted through the harness or reins connecting the horse to the cart, resulting in the forward motion of the cart. Options [A], [C], and [D] are not relevant to the forward motion of the cart. While the force of gravity and contact forces between the horse’s hooves and the ground play roles in facilitating motion, they are not the primary forces responsible for the cart’s forward movement. Therefore, the correct answer is [B] By the force applied by the horse on the cart.