Eutrophication from nutrient enrichment

Steps:

• Identify eutrophication as excessive algae growth leading to oxygen depletion in water bodies.
• Recognize causes involve nutrient overload, mainly nitrogen and phosphorus from human sources.
• Link to lakes: agricultural runoff introduces these nutrients.
• Match to options: nitrates from fertilizers directly cause this nutrient surge.

Why B is correct:

• Nitrate fertilizers provide excess nitrogen, fueling algal blooms as per the eutrophication definition of nutrient-driven ecosystem imbalance.

Why the others are wrong:

• A. Metal compounds cause toxicity but not nutrient-driven algal overgrowth.
• C. Oxygen is depleted by eutrophication, not its cause.
• D. Sulfuric acid leads to acidification, harming aquatic life without promoting algae.

Final answer: B