What processes contribute to summertime hypoxia in estuaries, and which environmental factor worsens it?

• A. Nutrient-driven algal blooms, subsequent decomposition consuming oxygen, and stratification that limits mixing; warming exacerbates stratification.
• B. Oxygen is generated by algae, reducing hypoxia.
• C. Hypoxia is solely caused by saltwater intrusion with no biological processes.
• D. Hypoxia is unrelated to temperature or nutrients.

Answer: (A)