farmers working to protect the environment. natural substances being used to solve problems. farmers trying to decrease the amount of crops. the solution for one problem creating another problem.
I gave my students this multiple choice question: Pesticides are used by farmers to control insects. Sometimes, the pesticides run off into streams. This is an example of

Only one answer is correct among these 4 choices:
- farmers working to protect the environment.
- natural substances being used to solve problems.
- farmers trying to decrease the amount of crops.
- the solution for one problem creating another problem.

Could you tell me which one is correct?

the solution for one problem creating another problem.