This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Concepts in physiology, Subject name: Physiology
Resting membrane potential is mainly due to: 
Select and explain. 
A. Na+, B. K+, C. Cl-, D. Ca++
B: K+
Answer: B: K+ 
Explanation: Nernst equilibrium potential for K+ =-94 mV is much close to RMP value of -90mV in nerves Nernst equilibrium potential for Na+= +61mv Hence RMP is close to or mainly due to K+ ion.