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
Maximum concentration of sodium channel is at 
Select and explain. 
A. Cell body at dendrite end, B. Initial segment, C. Axon below myelin, D. Node of ranvir
D: Node of ranvir
Answer: D: Node of ranvir 
Explanation: At the node of Ranvier, Na channels are 2000 to 12000/sq micrometer of membrane(Ref: Textbook of physiology N Geetha 2nd edition page no.4)