Biology

A.Eutrophication 

Explanation:

Eutrophication is the process by which excess nutrients, particularly nitrogen and phosphorus (often from fertilizers), enter water bodies such as lakes, rivers, and oceans. These nutrients promote the overgrowth of algae, leading to algal blooms. As the algae decompose, oxygen levels in the water decrease, often to the point where oxygen depletion causes "dead zones" where most aquatic life cannot survive.

The other terms refer to different...