This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Trauma, Subject name: Surgery
[{'content': 'Flail chest is defined as \nSelect and explain. \nA. Fracture of 3 or more ribs at 2 or more places, B. Fracture of 2 or more ribs at 2 or more places, C. Fracture of 2 or more ribs at one place, D. Fracture of multiple ribs at one place', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Flail chest : Fracture of two or more consecutive ribs, with each rib having two or more fracture sites. Such segment is called flail segment. Ref : SRB&;s 4thE pg:1196', 'role': 'assistant'}]