Fact 1: Adrought can change the color of an environment from green to brown.

Fact 2: Too little rain causes a drought.

Given the two facts above, answer the question "Too little of what can change the color of an environment from green to brown?" with the following options: 
- pool water
 - energy
 - bath water
 - Acids
 - algae
 - heat
 - water hose
 - rain


 

        rain 