Fact 1: Adoorbell converts electrical energy into sound.

Fact 2: Perception of sound Sound is a wave.

Given the two facts above, answer the question "What is created when a doorbell is pressed?" with the following options: 
- an object
 - particles
 - heat
 - energy
 - a wave
 - courtship
 - aura
 - colors


 

     a wave    