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: Medicine
[{'content': 'Which of the following is a poor prognostic factor in Acute Lymphoblastic Leukemia (ALL): \nSelect and explain. \nA. Hyperdiploidy, B. t (9; 22); t (4; 11), C. 2-8 years of Age, D. WBC count < 50,000', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Unourable cytogenetics in ALL are Philadelphia chromosomes t(9;22) & t(4;11) Ref: CMDT 2008 Edition, Page 447', 'role': 'assistant'}]