Fact 1: Aradio converts electrical energy into vibrations.

Fact 2: Ordinary hearing is the result of the stimulation of bones in the inner ear by means of vibration.

Given the two facts above, answer the question "What can human ears hear?" with the following options: 
- radio
 - time
 - waves
 - Frogs
 - Frogs.
 - light
 - xrays
 - sound


 

 radio        