Pollutant identification from ocean bay sources

Steps:

• Examine diagram sources like agricultural runoff, sewage, and urban discharge entering the bay.
• Match sources to common pollutants: farms and lawns indicate fertilizers with nitrogen.
• Link nitrogen to water pollution effects, such as eutrophication causing algal blooms.
• Eliminate gases or unrelated chemicals not tied to aquatic nutrient cycles.

Why D is correct:

• Nitrogen-containing chemicals, like nitrates from fertilizers, drive eutrophication in coastal waters per nutrient pollution definitions.

Why the others are wrong:

• A: Carbon dioxide is an atmospheric greenhouse gas, not a primary bay pollutant from shown sources.
• B: Insecticide is a pesticide from specific pest control, unrelated to broad nutrient runoff.
• C: Methane is a biogas from anaerobic decay, not typically entering bays via surface sources.

Final answer: D