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
Action of chlorine in water is through: 
Select and explain. 
A. Hypochlorous acid, B. HCL, C. Both of the above, D. None of the above
A: Hypochlorous acid
Answer: A: Hypochlorous acid 
Explanation: Hypochlorous acid