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
Concentration of sodium channel in nerve in per square foot is 
Select and explain. 
A. 1.6 x 10-5 to 1.9 X-2 per square foot, B. 6.6 x 10-6 to 3.9 X-3 per square foot, C. 1.6 x 10-6 to 1.9 X-3 per square foot, D. 6.6 x 10-5 to 3.9 X-2 per square foot
D: 6.6 x 10-5 to 3.9 X-2 per square foot
Answer: D: 6.6 x 10-5 to 3.9 X-2 per square foot 
Explanation: In myelinated neurons most sodium channels are present at nodes of ranvier Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:72,73