Which of the following natural systems could be affected by agricultural runoff from a large, heavily tilled farm?

a river ecosystem 5 miles from the farm
a wetland ecosystem 500 meters the farm
a marine ecosystem 200 miles from the farm
a freshwater lake ecosystem 50 miles from the farm

As agricultural runoff enters bodies of water it can have negative impacts on the environment. Not only can it contaminate sources of drinking water but the chemicals in the fertilizers can be absorbed into aquatic plants, contribute to algae blooms and effect animals' ability to find food and reproduce.