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
Which ion helps is resting membrane potential in neurons: September 2005, March 2013 
Select and explain. 
A. Potassium, B. Calcium, C. Chloride, D. Sodium
A: Potassium
Answer: A: Potassium 
Explanation: Ans. A: Potassium In neurons resting membrane potential is about -70 mV, which is close to the equilibrium potential of potassium ions