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: Pathology
[{'content': 'Which of the following is a specific marker for ewings sarcoma? \nSelect and explain. \nA. CD 45, B. CD 99, C. HMB-45, D. CD1a', 'role': 'user'}, {'content': 'Answer: B \nExplanation: CD 99 (MIC 2 ) is a specific marker for ewings sarcoma', 'role': 'assistant'}]