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': 'Sullivan index is an index for - \nSelect and explain. \nA. Life free of disability, B. Life expectancy, C. Earning capacity, D. Population index', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Life free of disability", 'role': 'assistant'}]