Eutrophication of a lake is typically caused by
- A
Acid rain (especially sulfur and nitrogen oxides) lowering pH and killing plankton populations
- B
Loss of top predators (especially fish) leading to algal grazer collapse and water clarity loss
- C
Thermal pollution (especially from power plants) raising water temperature and reducing oxygen
- Dcheck_circle
Excess nutrients (especially N and P) from runoff, causing algal blooms and oxygen depletion
Explanation
Fertilizer runoff or sewage causes algal blooms; when algae die and decompose, oxygen drops, killing fish (dead zones).