High value of BOD (Biochemical Oxygen Demand) indicates

The correct option is C Consumption of organic matter in the water is higher by the microbes
Biochemical Oxygen Demand or Biological Oxygen Demand is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms while decomposing organic matter in water. A high BOD indicates two things: -

1. There is a high level of microorganisms in the water, and

2. There is a high content of organic material in the water that is broken down by the organisms. This is an indication of organic pollution.

Thus, the correct answer is (B).