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
An ultrasound examination shows dilated intrahepatic biliary channels with a small gall bladder. The most likely possibility is - 
Select and explain. 
A. Gall Bladder stone, B. Pancreatic calculus, C. Common bile duct stone, D. Carcinoma of the head of the pancreas
C: Common bile duct stone
Answer: C: Common bile duct stone 
Explanation: Ans. is 'c' i.e. Common bile duct stone * In Ca Head of Pancreas, GB will also be distended.