This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gall Bladder & Bile Ducts, Subject name: Surgery
[{'content': 'Old male came with jaundice, palpable mass in the right hypochondrium not associated with pain. \nSelect and explain. \nA. Carcinoma Ampulla of Vaster, B. Acute cholecystitis, C. Chronic cholecystitis, D. Chronic pancreatitis', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Carcinoma Ampulla of VaterRef: Long cases surgery RRM* As per Courvoisier law"GB palpable is due to cancer-Distal CBD or Periampullary cancer"', 'role': 'assistant'}]