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: Dental
[{'content': 'The double pot method of adding chlorine to well water was devised by \nSelect and explain. \nA. WHO, B. UNICEF, C. National Environment Engineering and Research Institute, D. ICMR', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]