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: Orthopaedics
[{'content': 'According to a newer hypothesis Ewings, sarcoma arises from - \nSelect and explain. \nA. Epiphysis, B. Diaphysis, C. Medullary cavity, D. Cortex', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Marrow tumors (medullary cavity tumors) : - Ewings sarcoma, Plasma cell tumor, multiple myeloma, Lymphoma.', 'role': 'assistant'}]