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: Pathology
[{'content': 'A 65-year-old woman is found to have a 1-cm mass in the upper outer quadrant of the left breast. The most likely cause is \nSelect and explain. \nA. Fibrocystic disease., B. Acute mastitis., C. Fibroadenoma., D. Carcinoma.', 'role': 'user'}, {'content': "Answer: D \nExplanation: The location of the mass in the upper outer quadrant and the patient's age of 65 years suggest that the breast lesion is a carcinoma. A breast mass in a postmenopausal patient is most often a carcinoma.", 'role': 'assistant'}]