Which of the following statements best describes the effect of nutrient runoff on oxygen in water bodies?

• A. Nutrient runoff can lead to algal blooms and subsequent oxygen depletion, creating hypoxic zones.
• B. Nutrient runoff always increases dissolved oxygen.
• C. Nutrient runoff has no effect on oxygen levels.
• D. Nutrient runoff reduces nutrient levels in water.

Answer: (A)