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
[{'content': 'Resting membrane potential is mainly due to \nSelect and explain. \nA. Na+, B. K+, C. Cl-, D. Mg++', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Resting membrane potential depends on the concentration of potassium ion. (REF: TEXTBOOK OF MEDICAL PHYSIOLOGY GEETHA N 2 EDITION, 23)', 'role': 'assistant'}]