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': 'Non-myelinated  axons  differs  from myelinated in that they: \nSelect and explain. \nA. Are more excitable, B. Lack node of Ranvier, C. Are capable of regeneration, D. Are not associated with Schwann cells', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Remember,\xa0two\xa0types\xa0of\xa0Schwann\xa0cell: Myelinating and non\xadmyelinating types.\nIn the PNS, unmyelinated axons are surrounded\xa0by\xa0Schwann\xa0cells (non\xadmyelinating), whereas\xa0myelinated\xa0axons\xa0are\xa0ensheathed\xa0by\xa0multiple\xa0wrapped\xa0membranes\xa0of Schwann cells, much as the oligodendroglia, that ensheath\xa0central axons.', 'role': 'assistant'}]