You are presented with the question "What has a negative impact on forests?" and the following answer choices: 
- local fauna
 - local flora
 - humans disturb it
 - deforestation
 - erosion of soil
 - smallpox
 - local wildlife
 - vehicles

Now knowing that erosion of soil has a negative impact on the environment and forest environments collapse, choose the best answer.


 

     erosion of soil    