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 the most common mutation in Ewing's sarcoma - \nSelect and explain. \nA. Translocation X : 18, B. Translocation 11; 22, C. Activative mutation of G5alpha surface protein, D. Missense mutation in EXTI", 'role': 'user'}, {'content': "Answer: B \nExplanation: Ewing's sarcoma is typically characterized by a translocation t (11; 22) (q 24; q12) in up to 90% of patients.", 'role': 'assistant'}]