In water quality assessment, what is BOD and why is it important?

• A. Biological Oxygen Demand; the amount of oxygen required by microorganisms to decompose organic matter; indicates pollution level and potential aquatic stress.
• B. Basic Oxygen Dose; the amount of oxygen added to water to promote photosynthesis.
• C. Biochemical Oxygen Distribution; the spread of oxygen among water layers.
• D. Bacterial Oxygen Density; the concentration of bacteria in water.

Answer: (A)