Answer:
music amplifier or a loudspeaker
Explanation:
A music amplifier or a loudspeaker are a few devices that convert electrical energy into sound energy.
As it is a well known fact that energy can neither be created nor be destroyed it can only change from one form to the other. As here it is changing from electrical to sound.
The best answer that I can give you is, the Plate.
The answer to the question is letter b