You are presented with the question "Where photosynthesis occurs in a cactus, what is stored?" and the following answer choices: 
- glucose
 - flowers
 - water
 - sand
 - gametes
 - birds
 - lipids
 - energy

Now knowing that acactus stem is used for storing water and photosynthesis occurs on the green surface of the cactus stem, choose the best answer.


 

   water      