This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gallstone Disease, Subject name: Surgery
[{'content': 'MERCEDES BENZ sign seen In - \nSelect and explain. \nA. Volvulus, B. Gall stone, C. Struvite calculus, D. Intussuception', 'role': 'user'}, {'content': "Answer: B \nExplanation: Ans. is 'b' i.e., Gall stoneRemmeber :o Mercedes benz sign (Also known as Jack stone sign)On xray - Gall stonesOn echocardiography - Cross section of aortic valve", 'role': 'assistant'}]