This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Childhood Tumors, Subject name: Pediatrics
[{'content': "Most common cancer in children less than 10 years: \nSelect and explain. \nA. Leukemia, B. Neuroblastoma, C. Brain tumor, D. Wilm's tumor", 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Leukemia(Ref: Nelson's 20/e p 2437, Ghai 8/e 599-607)Most frequent childhood cancers are: (in order of decreasing frequency) Leukemia (Most common is ALL)Q > Neuroblastoma > Wilms' tumor > Hepatoblastoma > Retinoblastoma", 'role': 'assistant'}]