This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General physiology, Subject name: Physiology
[{'content': 'Fibres most sensitive to local anesthesia are \nSelect and explain. \nA. A, B. B, C. C, D. None', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Group C nerve fibers are one of three classes of nerve fiber in the central nervous system (CNS) and peripheral nervous system (PNS). The C group fibers are unmyelinated and have a small diameter and low conduction velocity, whereas Groups A and B are myelinated. Group C fibers include postganglionic fibers in the autonomic nervous system (ANS), and nerve fibers at the dorsal roots (IV fiber). These fibers carry sensory information C fibers and A-d are sensitive to local anesthesia Ref guyton and hall textbook of medical physiology Edition 12 pg 701 Group C nerve fiber C fiber not labeled, but substantia gelatinosa of Rolando is Rexed lamina II, labeled at upper left.', 'role': 'assistant'}]