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
Lymph nodes involved in anal Ca. Is 
Select and explain. 
A. Inguinal lymph nodes, B. Iliac lymph nodes, C. Para aortic, D. Subclavicular
A: Inguinal lymph nodes
Answer: A: Inguinal lymph nodes 
Explanation: Inguinal lymph nodes are involved in anal ca.