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': 'What is flail chest? \nSelect and explain. \nA. Fracture of three or more ribs at 2 or more places, B. Fracture of 2 ribs at three places, C. Ventilator associated pneumonia, D. Transfusion associated lung injury', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Fracture of three or more ribs at 2 or more placesRef: Bailey 26th edition Page 355* Flail chest is defined as three or more ribs fractured in two or more places', 'role': 'assistant'}]