This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Anatomy
[{'content': 'Most common site of cholangiocarcinoma \nSelect and explain. \nA. Distal biliary tract, B. Hilum, C. Intrahepatic duct, D. Multifocal', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Cholangiocarcinoma Tumors arising from bile duct epithelium. Most common type is adenocarcinoma Differentiated by anatomic site of origin: Intrahepatic (10%), Hilar (65%), and distal (25%) MC gene mutation is K-ras >p16(KRAP-16) Ref: Sabiston 20th edition Pgno :1514-1518', 'role': 'assistant'}]