This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gallstone Disease, Subject name: Surgery
Best way to confirm that no stones are left back in the CBD? 
Select and explain. 
A. Choledochoscope, B. Palpation, C. Cholangiogram, D. ERCP
C: Cholangiogram
Answer: C: Cholangiogram 
Explanation: Ans. is 'c' i.e., Cholangiogram o "An operative cholangiogram at time of cholecystectomy will also demonstrate presence or absance of bile duct stones".o "If a CBD exploration was performed and a T-tube left in place, a T-tube cholangiogram is done before its removal".