Q: You are presented with the quiz "Thirst is used to make animals realize they need to what?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "thirst is used to make an animal realize that it needs to replenish its bodily water by the body" and "water hydrates the cells". So, what's the best answer to the question?

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.
A:
hydrate their cells