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, which states that for every action, there is an equal and opposite reaction. When the person jumps down on the trampoline, they exert a force on the trampoline, and in response, the trampoline exerts an equal force upward on the person, propelling them into the air.