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 is most radioresistant? \nSelect and explain. \nA. Cailage, B. GIT epithelium, C. Gonadal tumours, D. Ewing's sarcoma", 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. Cailage', 'role': 'assistant'}]