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
Nerve depolarization is due to 
Select and explain. 
A. Opening of sodium channels, B. Opening of chloride channels, C. Opening of potassium channels, D. Opening of calcium channels
A: Opening of sodium channels
Answer: A: Opening of sodium channels 
Explanation: When sodium ion enters a cell the potential goes positive side and this is depolarization phase. (REF: TEXTBOOK OF MEDICAL PHYSIOLOGY GEETHA N 2 EDITION, PAGE NO - 26)