This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
Biological oxygen demand is calculated to know wastes - 
Select and explain. 
A. Organic, B. Inorganic, C. Total solid, D. None
A: Organic
Answer: A: Organic 
Explanation: Ans. is 'a' i.e.. Organic