If thirst is used to make animals realize they need to hydrate their cells, then thirst is used to make animals realize they need to what?

Answer choices:
- remove their cells
 - filter their beverages
 - recovery time from fatigue
 - reusing things
 - moisturize their eyes
 - hydrate their cells
 - Converting waste.
 - they body they live in

 

      hydrate their cells    