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
Predisposing factor for leukemia - 
Select and explain. 
A. Down syndrome, B. Lowe's syndrome, C. Fragile-x-syndrome, D. None
A: Down syndrome
Answer: A: Down syndrome 
Explanation: Ans. is 'a' i.e., Down syndrome