This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
[{'content': "The following are seen in Pneumoperitoneum except \nSelect and explain. \nA. Football sign, B. Till-aux sign, C. Rigler's sign, D. Cupola sign", 'role': 'user'}, {'content': "Answer: B \nExplanation: Signs of Pneumoperitoneum :\n\nFootball sign - Collection of air in the centre of abdomen over flied collection.\nRigler's sign - Visualisation of air outling bowel wall on either side.\nCupola sign - Large amount of gas under diaphragm.", 'role': 'assistant'}]