This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Anatomy
[{'content': 'An ultrasound examination shows dilated intrahepatic biliary channels with a small gallbladder. The most likely possibility is \nSelect and explain. \nA. Gallbladder stones, B. Pancreatic calculus, C. Common bile duct stone, D. Carcinoma of the head of the pancreas', 'role': 'user'}, {'content': 'Answer: C \nExplanation: DIAGNOSIS OF CBD STONE USG : first test, can document GB stones and estimate the CBD diameter A dilated bile duct (>8mm in diameter) in a patient with gallstones, jaundice and biliary pain is highly suggestive of choledocholithiasis MRCP : Provides excellent anatomic detail, with sensitivity and specificity of 95 %and 98 %respectively, and CBD stones ERCP :Diagnostic and therapeutic test of choice for patients with suspected CBD stones Ref: Sabiston 20th edition Pgno :1494', 'role': 'assistant'}]