Eutrophication sequence from nutrient runoff

Steps:

• Excess nitrogen boosts algae growth (4).
• Dense algae block sunlight (3).
• Aquatic plants die from lack of light (5).
• Bacteria decompose dead matter, consuming oxygen (1).
• Oxygen depletion causes animal death or migration (2).

Why C is correct:

• C follows the eutrophication definition: nutrient enrichment triggers algal bloom, shading and plant death, microbial decomposition depleting dissolved oxygen, and hypoxic conditions harming fauna.

Why the others are wrong:

• A starts with bacterial oxygen use, skipping initial algal bloom.
• B begins with light blockage, ignoring prior algae proliferation.
• D opens with plant death, which occurs after shading by algae.

Final answer: C