This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Concept of health and disease, Subject name: Social & Preventive Medicine
[{'content': 'In sample registration system independent survey is done at every \nSelect and explain. \nA. 2 months, B. 6 months, C. 12 months, D. 2 years', 'role': 'user'}, {'content': 'Answer: B \nExplanation: SRS is a dual record system initiated to provide reliable estimates of bih and death rates.It consists of a continuous enumeration of bihs and deaths by an enumerator and an independent survey every 6 months by an investigator-supervisor.Park 23e pg: 841', 'role': 'assistant'}]