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': 'In choledochal cyst, most common type is: \nSelect and explain. \nA. Type 1, B. Type 2, C. Type 4, D. Type 4A', 'role': 'user'}, {'content': "Answer: A \nExplanation: Type 1 is the most common type and constitute about 50% of the choledochal cysts. Type 5 is dilation confined to intrahepatic bile ducts (caroli's disease). Ref: Sabiston, 18th Edition, Page 1577", 'role': 'assistant'}]