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': "Radiographically 'Sequestrum' formed in osteomyelitis is: \nSelect and explain. \nA. More opaque than healthy bone, B. Same opaque than healthy bone, C. Less opaque than healthy bone, D. None of the above", 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]