This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bile duct, Subject name: Surgery
[{'content': "Which of the following is an exception of Courvoisier's law? \nSelect and explain. \nA. Double Impaction, B. Poal lymphadenopathy, C. Periampullary Carcinoma, D. None of the above", 'role': 'user'}, {'content': "Answer: A \nExplanation: Exceptions to courvoisier's Law Double impaction of stones i.e. one in the cystic duct and other in CBD. Oriental cholangiohepatitis Pancreatic calculus obstructing the ampulla of Vater Mucocele due to stone in the cystic duct", 'role': 'assistant'}]