Why Is the Runoff from Fertilized Agricultural Fields, Even If

Multiple Choice

Why is the runoff from fertilized agricultural fields, even if free of pesticides, often harmful to the ecosystems of temperate lakes?

A) Fertilizer compounds are toxic to fish.
B) The runoff causes heavy growth of algae, which eventually die and decompose, causing oxygen depletion.
C) Runoff water pools at the lake's bottom, where the fertilizer compounds react with materials in the sediment to form toxic substances.
D) The runoff is acid, and acidification kills key lake organisms.