- A The water is unusually clean and contains abundant dissolved oxygen
- B Greater level of organic pollution requiring more oxygen
- C The presence of dissolved heavy metals such as lead and mercury
- D An unusually low level of bacterial metabolic activity in the sample
Correct answer: B. Greater level of organic pollution requiring more oxygen
Explanation: A higher BOD indicates more organic matter present in water, requiring more oxygen for microbial decomposition, signifying greater pollution.
Concept context
Microorganisms in food, medicine, sewage treatment, biocontrol, and biofertilizers