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: Surgery
Which of the following is the most common astrocytoma in children? 
Select and explain. 
A. Grade 1 astrocytoma, B. Grade 2 astrocytoma, C. Grade 3 astrocytoma, D. Grade 4 astrocytoma
A: Grade 1 astrocytoma
Answer: A: Grade 1 astrocytoma 
Explanation: Pilocytic astrocytoma (Grade 1) is the most common astrocytoma in children.