Fact 1: Acactus stem is used for storing water.

Fact 2: Cactuses exemplify water conservation.

Given the two facts above, answer the question "a cactus stem is used for what?" with the following options: 
- Plants growth
 - nutrients
 - kinetic energy
 - energy
 - growth
 - conservation
 - flow of electrons
 - organic molecules


 

      conservation   