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': 'The fastest type of nerve fibers are \nSelect and explain. \nA. A, B. B, C. C, D. All', 'role': 'user'}, {'content': 'Answer: A \nExplanation: According to erlanger and gasser classification, A fibers are myelinated and has large diameter The conduction velocity is 120m per second Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:73', 'role': 'assistant'}]