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: Anatomy
[{'content': 'Posterior relation of hilum of lung ? \nSelect and explain. \nA. Azygous vein, B. SVC, C. Vagus nerve, D. Arch of aoa', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Vagus nerve', 'role': 'assistant'}]