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: Physiology
[{'content': 'In CNS, the myelination is carried out by: \nSelect and explain. \nA. Schwann cells, B. Astrocytes, C. Oligodendrocytes, D. Microgila', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]