This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal Radiology, Subject name: Radiology
[{'content': 'Bowler hat sign is seen in \nSelect and explain. \nA. Sigmoid volvulus, B. Midgut volvulus, C. Intussusception, D. Sessile colonic polyp', 'role': 'user'}, {'content': 'Answer: D \nExplanation: BOWLER HAT SIGN: Cup shaped filled defect seen on air contrast barium enema that represents POLYP if it points towards lumen. The "bowler-hat sign" represents the appearance of a sessile colonic polyp observed at an oblique angle on a double contrast barium enema. The bowler-hat sign is formed by a ring of barium adjacent to the base of the polyp surrounding a domed layer of barium coating the surface of the polyp.', 'role': 'assistant'}]