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
Which is the most common cause of bloody discharge of breast from a single duct? 
Select and explain. 
A. Duct papilloma, B. Duct ectasia, C. Breast cancer, D. Paget’s disease
A: Duct papilloma
Answer: A: Duct papilloma 
Explanation: Bloody discharge from a single duct cause is duct papilloma, if multiple ducts involved then the most common cause is breast cancer.