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: Surgery
[{'content': 'Which is the most common cause of bloody discharge of breast from a single duct? \nSelect and explain. \nA. Duct papilloma, B. Duct ectasia, C. Breast cancer, D. Paget’s disease', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Bloody\xa0discharge from a single duct cause is duct papilloma, if multiple ducts involved then the most common cause is breast cancer.', 'role': 'assistant'}]