Which of the following is most likely to occur when excess fertilizer make their way into the waterways through run off

Eutrophication

Explanation:

When a body water lies in close proximity to any agricultural land, there are high chance of it receiving nutrient from the surrounding land in rainy season. The rich nutrient run off from these land parcels, mixes with the water of existing water body and make it extremely rich in growth nutrients. The excess of nutrients causes uninterrupted growth of algae and lead to algal boom. Oxygen in such water bodies depletes at a fast rate due to the increased productivity thereby harming the water animals living in it.