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
Most common malignant tumor of kidney in children is: 
Select and explain. 
A. Renal cell carcinoma, B. Mesoblastic nephroma, C. Wilm's tumour, D. None of the above
C: Wilm's tumour
Answer: C: Wilm's tumour 
Explanation: Wilms' tumor is the most common primary malignant tumor of the kidney in children. Ref: Schwaz's principle of surgery 9th edition, chapter 39.