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
The most common cause of suppurative cholangitis is - 
Select and explain. 
A. Stone in common bile duct, B. Cancer of the ampulla of vater, C. Choledochal cyst, D. Empyema of gall bladder
A: Stone in common bile duct
Answer: A: Stone in common bile duct 
Explanation: None