Choose from: [I] tree bark [II] leaf [III] fur and fat [IV] Heat energy [V] Calcium carbonate [VI] tree branch [VII] mussels [VIII] a cactus stem

Fact 1: Acactus stem is used for storing water. Fact 2: Drink lots of water for hydration. Given the two facts above, what can be used for hydration?
Answer:
[VIII]