Fact 1: Conserving water can be used for survival in a dry environment.

Fact 2: Conservation of water follows conservation of sodium.

Given the two facts above, answer the question "Conserving what can be used for survival in a dry environment?" with the following options: 
- bamboo
 - Collagen
 - root
 - sodium
 - cellulose
 - energy
 - salinity
 - Conifers


 

    sodium     