Fact 1: Hearing is used for sensing sound by animals.

Fact 2: An ear improves hearing.

Given the two facts above, answer the question "What does an ear improve?" with the following options: 
- activation energy
 - Relieve pain
 - Sensing sound
 - looseness
 - vision
 - Sensing wavelengths
 - nervous system
 - sight


 

   Sensing sound      