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': 'Which of the following glial cells helps in myelination of CNS neurons? \nSelect and explain. \nA. Astrocytes, B. Schwann cells, C. Microglial cells, D. Oligodendrocytes', 'role': 'user'}, {'content': 'Answer: D \nExplanation: None', 'role': 'assistant'}]