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
Best treatment modality for common bile duct stone is - 
Select and explain. 
A. Endoscopic sphincterotomy, B. Observation, C. Chenodeoxycholic acid, D. Percutaneous removal
A: Endoscopic sphincterotomy
Answer: A: Endoscopic sphincterotomy 
Explanation: None