You are presented with the question "what in the inner ear is used for sensing sound by animals?" and the following answer choices: 
- neurons
 - Frogs.
 - tube
 - Frogs
 - fluid
 - fibers
 - energy
 - motors

Now knowing that hearing is used for sensing sound by animals and for example, hearing waves are transmitted by fluid in the inner ear, choose the best answer.


 

     fluid    