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
The fastest type of nerve fibers are 
Select and explain. 
A. A, B. B, C. C, D. All
A: A
Answer: A: A 
Explanation: 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