This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Small & Large Intestine, Subject name: Surgery
[{'content': "Etiology for this condition: \nSelect and explain. \nA. Adhesive obstruction, B. Sigmoid volvulus, C. Meckel's diverticulum, D. Gastric volvulus", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. (b) Sigmoid volvulusRef: Bailey and Love 26th edition, Page 1195* Most common site of volvulus in colon -- sigmoid* Most common direction of volvulus is anticlockwise > Clockwise* X-ray shows --Coffee-bean or bent inner tube sign* Barium enema shows -- Bird beak sign', 'role': 'assistant'}]