This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2017, Subject name: Social & Preventive Medicine
[{'content': 'Sample registration is done \nSelect and explain. \nA. Every 3 months, B. Every 6 months, C. Every 9 months, D. Every 12 months', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Sample registration system (SRS) SRS is taken once every 6 months It is a dual record data collection system of India Therefore, it is the most accurate data collection system of India', 'role': 'assistant'}]