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
[{'content': "To find out whether the water has been properly chlorinated, the test used is - \nSelect and explain. \nA. Horrock's test, B. Oho-toludine test, C. Presumptive col i form test, D. Total bacterial count", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Oh o-toludine test", 'role': 'assistant'}]