This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bile duct, Subject name: Surgery
[{'content': 'Which of the following is not formed sphincter of oddi complex? \nSelect and explain. \nA. Sphincter pancreaticus, B. Sphincter ampullae, C. Superior choledochal sphincter, D. Posterior choledochal sphincter', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Sphincter of oddi complex:- 1. sphincter ampullae 2. sphincter pancreaticus 3. superior choledochal sphincter 4. inferior choledochal sphincter', 'role': 'assistant'}]