This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urinary tract, Subject name: Pathology
Percentage of renal vein involvement in renal cell carcinoma is - 
Select and explain. 
A. 2%, B. 8%, C. 16%, D. 32%
B: 8%
Answer: B: 8% 
Explanation: 8% Renal cell carcinoma with renal vein and inferior vena cava involvement Ref: