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: Radiology
[{'content': 'Hallmark feature of osteomyelitis is: \nSelect and explain. \nA. Identification of sequestrum, B. Pain, C. Swelling, D. None of the above', 'role': 'user'}, {'content': "Answer: A \nExplanation: The hallmark of osteomyelitis is the development of sequestra. A sequestrum is a segment of bone that has become necrotic because of ischemic injury caused by the inflammatory process.\nReference: White and Pharoah's Oral Radiology Principles and Interpretation 7th edition page no 320", 'role': 'assistant'}]