This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Surgery
[{'content': 'A patient with history of choledocholithiasis presents with elevated conjugated bilirubin. Ultrasound reveals a dilated biliary system upto the terminal pa. In case of suspicion of an ampullary obstructive calculus which of the following investigations would be most sensitive? \nSelect and explain. \nA. PTC, B. MRCP, C. Xray abdomen, D. Endoscpic USG', 'role': 'user'}, {'content': 'Answer: D \nExplanation: EUS- Most sensitive method to detect ampullary stones', 'role': 'assistant'}]