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': 'Which pa of chlorine disinfection is most effective?- \nSelect and explain. \nA. Hypochlorous acid, B. Hypochlorous ion, C. Hypochlorite ion, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The disinfecting action of chlorine is mainly due to hypochlorous acid. It is 70-80 times effective than hypochlorite ion. So chlorine acts as best disinfectant a when pH of water is around 7 because of the predominance of hypochlorous acid. (PARK TB 25th edition pg 774)', 'role': 'assistant'}]