This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Neoplastic disorders of WBCs, Subject name: Pediatrics
Most common type of ALL in children: 
Select and explain. 
A. Pre-B cell ALL, B. Mature B cell ALL, C. Pre-T cell ALL, D. Mature T cell ALL
A: Pre-B cell ALL
Answer: A: Pre-B cell ALL 
Explanation: - 85% cases of ALL are pre-B-ALL - 15% are T-ALL and 1% are derived from mature B cells