This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
Non-myelinated  axons  differs  from myelinated in that they: 
Select and explain. 
A. Are more excitable, B. Lack node of Ranvier, C. Are capable of regeneration, D. Are not associated with Schwann cells
B: Lack node of Ranvier
Answer: B: Lack node of Ranvier 
Explanation: Remember, two types of Schwann cell: Myelinating and non­myelinating types.
In the PNS, unmyelinated axons are surrounded by Schwann cells (non­myelinating), whereas myelinated axons are ensheathed by multiple wrapped membranes of Schwann cells, much as the oligodendroglia, that ensheath central axons.