Final answer:
In the scenario where a cart is hit by another cart, key forces include the force of collision and internal forces such as normal force and friction. Gravitational force is also present, along with a normal force from the cart's floor.
Step-by-step explanation:
When a cart with two boxes and a bouncy ball is hit by another cart, several forces act on the cart that was hit. The correct answer would be none of the listed options (A, B, C) directly. Instead, the key forces involved are the force of the collision applied by the other cart and the internal forces between the objects on the cart, such as normal force, friction, and tension if there are strings or connectors inside the cart. Gravitational force acts on all the objects on the cart, providing a downward force, and this is often counteracted by the normal force from the floor of the cart. If the collision is perfectly elastic, momentum and energy are conserved; however, if it is inelastic, such as when the carts stick together, the total kinetic energy is not conserved, although momentum still is.