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: Pathology
[{'content': "Histology of Myositis ossificans mimics - \nSelect and explain. \nA. Osteosarcoma, B. Osteochondroma, C. GCT, D. Ewing's tumour", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Histologically myositis ossificans mimics osteosarcoma.\nThey can be differentiated by zone phenomenon :-\n\nOsteogenic sarcoma →\xa0Central zone contains mature cells and peripheral zone contains more active immature cells.\nMyositis ossificans\xa0→\xa0Central zone contains active immature cells and peripheral zone contains more mature cells.', 'role': 'assistant'}]