Eutrophication is the excessive richness of nutrients in a body of water, frequently leading to algal blooms and subsequent oxygen depletion (hypoxia). Which group of substances primarily acts as the nutrient pollutant in this process, often originating from agricultural runoff?

💡 Explanation:

Eutrophication is driven by excessive nutrient loading. Nitrogen and phosphorus, primarily sourced from agricultural fertilizers and sewage, stimulate rapid algal growth (algal blooms). When these algae die and decompose, the process consumes vast amounts of dissolved oxygen, leading to hypoxic conditions or 'dead zones.'