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': 'Which does not contribute to enterobiliary fistula \nSelect and explain. \nA. Gastric ulcer, B. Duodenal ulcer, C. Carcinoma gallbladder, D. Gallstones', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Internal biliary fistula Cholecystoduodenal fistula(72-80%) are MC biliary enteric fistulas followed by cholecysticolic fistula (8-12%). Etiology Calculous biliary tract disease (90%). Duodenal ulcer(6%) Neoplasm, trauma, Parasitic infestation and congenital anomalies (4%) Ref : Sabiston 20th edition Pgno :1507', 'role': 'assistant'}]