Final answer:
According to Newton's Third Law of Motion, when a large truck pushes a small car, the small car applies an equal and opposite force on the truck.
Step-by-step explanation:
When a large truck pushes a small car with a given force, the small car is applying a reaction force and an equal force in the opposite direction on the truck. This is known as Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction.