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 "What can change the color of an environment from green to brown?" with the following options: 
- harmful substances
 - clouds
 - Greenhouse gasses
 - blizzards
 - deforestation
 - Greenhouse gases
 - blue skies
 - too little rain


 

        too little rain 