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
[{'content': 'Best vein for total parenteral nutrition is - \nSelect and explain. \nA. Subclavian vein, B. Femoral vein, C. Brachial, D. Saphenous', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The preferred site for central vein infusion is the superior vena cava & preferred access sites are subclavian > jugular > femoral vein.', 'role': 'assistant'}]