This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
[{'content': 'Mammography is used for screening from \nSelect and explain. \nA. 20 years, B. 30 years, C. 40 years, D. 50 years', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. (c) 40 years(Ref Schwartz page 513/ 10th edition)* American Cancer Society (ACS) recommends screening from 40 years* Other many recommend - from 50 years. (But Sabiston 20th edition also recommends 40 years - so let us go with 40 years)', 'role': 'assistant'}]