This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Most common bile duct tumor is \nSelect and explain. \nA. Adenocarcinoma, B. Squamous cell carcinoma, C. Transitional cell carcinoma, D. All', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Refer Robbins page no 874', 'role': 'assistant'}]