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': "CD-99 is the marker for: \nSelect and explain. \nA. Ewing's sarcoma, B. SLL, C. Dermatofibroma protruberans, D. Malignant histiocytic fibroma", 'role': 'user'}, {'content': 'Answer: A \nExplanation: . Ewing&;s sarcoma', 'role': 'assistant'}]