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': 'Ideally immunization against poliomyelitis should be staed at: September 2004 \nSelect and explain. \nA. Bih, B. 6 weeks, C. 12 weeks, D. 9 months', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. A i.e. Bih', 'role': 'assistant'}]