The correct option is A Petroleum industry
Biochemical Oxygen Demand (BOD) may not be a good index for pollution for water bodies receiving effluents from the petroleum industry. Biochemical oxygen demand is the amount of dissolved oxygen needed by aerobic biological organisms to break down organic material. But biochemical oxygen demand may not be a good index for pollution for water bodies receiving effluents from the petroleum industry because they only contain waste which is non-biodegradable.
Sewage water, industrial and dairy industry have biodegradable material which can be broken down by bacteria and in this process, oxygen is consumed. Thus lowering the dissolved oxygen in the water.