Fact 1: Acactus stem is used for storing water.

Fact 2: Some plants, like cactus, have a water storage system.

Given the two facts above, answer the question "Where do some plants store their water?" with the following options: 
- loose soil
 - In their stem
 - peachleaf willow
 - barrel-shaped
 - watershed
 - near the shoreline
 - dormant state
 - by indirect light


 

  In their stem       