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
[{'content': 'Investigation of choice in detecting small para-aoic lymph node is \nSelect and explain. \nA. Ultrasound scan, B. CT scan, C. Lymphangiography, D. Aeriography', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Investigation of choice in detecting small para-aoic lymph node: CT scan', 'role': 'assistant'}]