This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Membrane potiential, Subject name: Physiology
[{'content': 'Among the ions mentioned, the highest equilibrium potential is for: \nSelect and explain. \nA. Na+, B. K+, C. Ca++, D. H+', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Equilibrium potential for Ca2+ = +129 mV. Two factors are responsible for this high value: 1.Calcium is a divalent cation. 2.Its concentration gradient (ECF:ICF) is very large.', 'role': 'assistant'}]