This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Non communicable diseases, Subject name: Social & Preventive Medicine
[{'content': 'Disability was added in census from which year- \nSelect and explain. \nA. 1981, B. 1991, C. 2001, D. 2011', 'role': 'user'}, {'content': 'Answer: A \nExplanation: First disability census was taken in 1981', 'role': 'assistant'}]