A) Increased oxygen levels in a pond due to fertilizer run off
Explanation:
When fertilizer is applied to a farm during the day, rain could fall after the application, and as a result of errosion, some amount of the fertilizer could be washed away into the ponds due to run off, and some of the chemical components of fertilizer are poisonous to the fish, development of algae in the pond can reduce light needed in by the fish and oxygen could as well be reduced.
