allowing beavers to build a dam spreading fertilizer near the river mowing the grass on the river bank fishing from a bridge over the river
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following would be more likely to pollute a river?
Possibilities:
- allowing beavers to build a dam
- spreading fertilizer near the river
- mowing the grass on the river bank
- fishing from a bridge over the river

spreading fertilizer near the river