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: Pediatrics
[{'content': "All are associated with malignancy except : \nSelect and explain. \nA. Down's syndrome, B. Fragile X syndrome, C. Bloom syndrome, D. Fanconi's anaemia", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Has been explained (see factors predisposing to childhood leukemia).', 'role': 'assistant'}]