This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Vascular surgery, Subject name: Surgery
Investigation of choice in detecting small para-aoic lymph node is 
Select and explain. 
A. Ultrasound scan, B. CT scan, C. Lymphangiography, D. Aeriography
B: CT scan
Answer: B: CT scan 
Explanation: Investigation of choice in detecting small para-aoic lymph node: CT scan