Fact 1: Erosion of soil has a negative impact on the environment.

Fact 2: Desertification implies soil erosion.

Given the two facts above, answer the question "what has a negative impact on the environment?" with the following options: 
- deforestation
 - deserts
 - cigarettes
 - desertification
 - humans disturb it
 - environments
 - weather
 - harmful substances


 

    desertification     