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
In prostate Ca. metastasis, lymph nodes most commonly affected are 
Select and explain. 
A. Sacral LN, B. Obturator LN, C. Paraaortic LN, D. Iliac LN
B: Obturator LN
Answer: B: Obturator LN 
Explanation: Obturator LN are first nodes involved in prostate Ca.