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

Fact 2: Due to the drought, there is no water.

Given the two facts above, answer the question "What can change the color of an environment from green to brown?" with the following options: 
- the ocean
 - a lack of water
 - rain
 - harmful substances
 - sleet
 - deforestation
 - Greenhouse gases
 - Greenhouse gasses


 

  a lack of water       