Fact 1: Adoorbell converts electrical energy into sound.

Fact 2: Alerting devices inform a person when the doorbell rings, alarm clock sounds, or telephone rings.

Given the two facts above, answer the question "Alerting devices inform a person when they convert electrical energy into what" with the following options: 
- sound
 - batteries
 - air
 - heat
 - energy
 - action
 - photons
 - waves


 

 sound        