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': 'Purpose of sentinel surveillance is - \nSelect and explain. \nA. To know total number of cases, B. Health planning, C. Prevention of disease, D. To know natural history of disease', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., To know total number of cases o The sentinel data is extrapolated to the entire population to estimate the disease prevalence in the total population. So, it helps in estimating the total amount of disease in a community.", 'role': 'assistant'}]