This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nervous system, Subject name: Physiology
[{'content': 'Myelin in CNS \nSelect and explain. \nA. Oligodendrocyte, B. Schwann cell, C. Astrocyte, D. Microglia', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Oligodendrocytes - myelin formation in cnsSchwann cells - myelin formation in pns Ref: Ganong&;s review of medical physiology; 23rd edition; pg:80', 'role': 'assistant'}]