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': 'Which of the following malignant tumors is radio resistant? \nSelect and explain. \nA. Ewing Tumour, B. Retinoblastoma, C. Osteosarcoma, D. Neuroblastoma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]