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 in the posterior mediastinum is: \nSelect and explain. \nA. Neurofibroma, B. Teratoma, C. Lymphoma, D. Bronchogenic cyst', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Most common tumors in the posterior mediastinum are Neurogenic tumors.\nSchwannomas (neurilemmomas) and neurofibromas are the most common neurogenic tumors in adults.\nNeurogenic tumors consist of tumors :\n\n\nOriginating from sympathetic ganglia : ganglioma, ganglioneuroblastoma and neuroblastoma.\nOriginating from intercostal nerves : Schwannoma (neurilemoma), neurofibroma & neurosarcoma.\nOriginating from paraganglia cells - paraganglioma', 'role': 'assistant'}]