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
Which of the following is not formed sphincter of oddi complex? 
Select and explain. 
A. Sphincter pancreaticus, B. Sphincter ampullae, C. Superior choledochal sphincter, D. Posterior choledochal sphincter
D: Posterior choledochal sphincter
Answer: D: Posterior choledochal sphincter 
Explanation: Sphincter of oddi complex:- 1. sphincter ampullae 2. sphincter pancreaticus 3. superior choledochal sphincter 4. inferior choledochal sphincter