This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Brainstem, cerebellum and ventricles, Subject name: Anatomy
Which cranial nerve's fibers are myelinated by oligodendrocytes? 
Select and explain. 
A. I, B. II, C. III, D. VII
B: II
Answer: B: II 
Explanation: The fibers of the optic nerve (CN II) are myelinated by oligodendrocytes. This is an impoant distinction from the Other cranial nerves ( myelinated by Schwann cells) because the optic nerve is considered a tract of the central nervous system