degradation of nutrients due to pesticides formation of deserts due to tree felling flooding due to dam construction removal of nutrients due to heavy rains
I gave my students this multiple choice question: Soils change both through natural processes and as a result of human activity. Which of the following soil changes is due only to natural causes?

Only one answer is correct among these 4 choices:
- degradation of nutrients due to pesticides
- formation of deserts due to tree felling
- flooding due to dam construction
- removal of nutrients due to heavy rains

Could you tell me which one is correct?

removal of nutrients due to heavy rains