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': 'The most common primary tumor of mediastinum \nSelect and explain. \nA. Lymphoma, B. Teratoma, C. Neurogenic tumor, D. Thymoma', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]