The best statement describing how this demonstrates Newton’s third law is:
The trampoline pushes back with equal force but in the opposite direction.
This statement accurately reflects Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. When the person jumps down onto the trampoline, they exert a downward force on it, and in response, the trampoline exerts an equal upward force, propelling the person upwards.