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': 'Zero dose of Polio vaccine in which is given: \nSelect and explain. \nA. Before giving DPT, B. At bih, C. When child is having diarrhoea, D. When child is having polio', 'role': 'user'}, {'content': 'Answer: B \nExplanation: At bih', 'role': 'assistant'}]