This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Head and neck, Subject name: Surgery
[{'content': 'Commonest spinal tumour is \nSelect and explain. \nA. Neuroblastomas, B. Neurofibroma, C. Ependymoma, D. Meningioma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Remember: Most Common Spinal tumor - Metastasis Primary spinal tumor - Nerve sheath tumor (Neurofibromas, Schwannoma Extradural tumor - Metastasis Intradural extramedullary - Nerve sheath tumor Intramedullary - Ependymoina Ref : Schwaz surgery 7/e p1891', 'role': 'assistant'}]