releasing warm water into the stream driving cars through the stream reducing use of fertilizers near the stream increasing use of chemicals near the stream
I gave my students this multiple choice question: Which human activity would have the greatest positive impact on the water quality of a stream?

Only one answer is correct among these 4 choices:
- releasing warm water into the stream
- driving cars through the stream
- reducing use of fertilizers near the stream
- increasing use of chemicals near the stream

Could you tell me which one is correct?

reducing use of fertilizers near the stream