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: Forensic Medicine
[{'content': 'Flail chest means fracture of: PGI 12 \nSelect and explain. \nA. Two ribs on same side, B. Two ribs on opposite side, C. Four ribs on two sides, D. All', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. Four ribs on two sides', 'role': 'assistant'}]