This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Tumors, Subject name: Orthopaedics
[{'content': 'Which of the following is associated with poor prognosis in Ewings sarcoma? \nSelect and explain. \nA. B2 microglobulin, B. Fever, C. Thrombocytosis, D. Young age', 'role': 'user'}, {'content': 'Answer: B \nExplanation: IMAGE SHOWS PROGNOSTIC FACTORS OF EWINGS SARCOMA REF : MAHESWARI 9TH ED', 'role': 'assistant'}]