You are presented with the question "what can change the color of an environment from green to brown?" and the following answer choices: 
- lack of rain
 - deforestation
 - precipitation
 - Greenhouse gases
 - climate
 - h2o
 - forests
 - swamp vegetation

Now knowing that adrought can change the color of an environment from green to brown and lack of rain last winter has intensified Arizona's drought, choose the best answer.


 

 lack of rain        