BOD is concerned with
1)	Microbes	2)	Organic matter
3)	Microbes and organic matter	4)	None of the above

Biochemical Oxygen Demand (BO4) is a measure of pollution by organic matter present in a sample of water

BOD is higher in polluted sewage water and is connected with both microbes and organic matter. More the organic pollution, specially sewage, more would be the BOD of water