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': "Rigler's triad consists of all except \nSelect and explain. \nA. Intestinal obstruction, B. Gas in bile duct, C. Cholangitis, D. Ectopic gallstone", 'role': 'user'}, {'content': "Answer: C \nExplanation: Gall stone ileus Passage of stone through a spontaneous biliary-enteric fistula leading to a mechanical bowel obstruction Clinical features Rigler's triad : Classic plain abdominal film triad of small bowel obstruction, pneumobilia & ectopic gallstone Ref: Sabiston 20th edition Pgno :1506-1507", 'role': 'assistant'}]