Fact 1: Acactus stem is used for storing water.

Fact 2: Drink lots of water for hydration.

Given the two facts above, answer the question "What can be used for hydration?" with the following options: 
- tree bark
 - leaf
 - fur and fat
 - Heat energy
 - Calcium carbonate
 - tree branch
 - mussels
 - a cactus stem


 

        a cactus stem 