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

Fact 2: Lack of rain last winter has intensified Arizona's 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: 
- lack of rain
 - deforestation
 - precipitation
 - Greenhouse gases
 - climate
 - h2o
 - forests
 - swamp vegetation


 

 lack of rain        