This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Skeletal System, Subject name: Radiology
[{'content': "Cleavage plane sign is seen in? \nSelect and explain. \nA. Parosteal osteosarcoma, B. Ewing's sarcoma, C. Chondrosarcoma, D. Metastasis", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans AParaosteal sarcoma arises exophytically from long bones and thus there is a small plane of cleavage between it and the main shaft of bone - the Cleavage plane sign.', 'role': 'assistant'}]