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
The diameter of Type C fibers is 
Select and explain. 
A. 13-20mm, B. 4-13mm, C. 3-6mm, D. 0.5-2mm
D: 0.5-2mm
Answer: D: 0.5-2mm 
Explanation: Unmyelinated fibers carrying pain, itch, temperature, and crude touch sensations (0.5 to 2 micrometers in diameter; they are type C fibers in the generalclassification).Ref: Guyton; 13th edition; Chapter 47 Sensory Receptors, Neuronal Circuits for Processing Information