An elastic collision is characterized by the conservation of both momentum and kinetic energy. Among the options you provided, the scenario that best represents an elastic collision is "a ping-pong paddle hitting a ball." In this case, while there is some energy lost to deformation and sound, the ball can return to its original shape and bounce back, which makes it closer to being elastic compared to the other options.
The other scenarios involve significant energy loss due to deformation (like the modeling clay), gravitational potential energy conversion (the falling apple), or sound and deformation (in the case of two hands clapping), making them largely inelastic.