This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment and health, Subject name: Social & Preventive Medicine
[{'content': 'The minimum recommended conecntration of free chlorine (mg/L) in drinking water at the end of 1 hour is - \nSelect and explain. \nA. 0.1, B. 0.5, C. 1, D. 1.5', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Recommended contact period of free residual Chlorine in water : 1 hour Level of free residual chlorine (FRC) recommended : Water type Residual chlorine level (Recommended) Contact period Drinking water >0.5 mg per litre (ppm) 1 hour Water bodies, post disaster >0.7 mg per litre (ppm) 1 hour Swimming pool sanitation >1.0 mg per litre (ppm) 1 hour Ref: Park 25th edition Pgno : 752', 'role': 'assistant'}]