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': 'Most common tumor of middle mediastinum: \nSelect and explain. \nA. Pericardial cyst, B. Aneurysm, C. Mesenchymal tumors, D. Lymphoma', 'role': 'user'}, {'content': 'Answer: D \nExplanation: MC common tumor of Middle Mediastinum: Lymphoma.\nMC common mass of Middle Mediastinum: Brachogenic cyst***.', 'role': 'assistant'}]