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: Surgery
[{'content': 'Saccular diveiculum of extrahepatic bile duct in choledochal cyst is classified as \nSelect and explain. \nA. Type I, B. Type II, C. Type III, D. Type IV', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Type 1b -saccular dilatation of extrahepatic biliary tree, Type 2-diveiculum of extrahepatic biliary tree Type 3-cystic dilatation of intraduodenal pa of CBD Type 4- dilatation of multiple pas of an extrahepatic biliary tree, dilatation of intrahepatic and extrahepatic biliary tree. Reference SRB edition 5. page637', 'role': 'assistant'}]