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': 'Pre tracheal and para tracheal LN are \nSelect and explain. \nA. Level I, B. Level II, C. Level IV, D. Level VI', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]