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
Investigation of choice in detecting small para-aortic lymph node is - 
Select and explain. 
A. Ultra sound scan, B. CT scan, C. Lymphangiography, D. Arteriography
B: CT scan
Answer: B: CT scan 
Explanation: • Investigation of choice in detecting small para-aortic lymph node: CT scan