This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Excitation and Action Potiential, Subject name: Physiology
[{'content': 'A 56-year-old woman with severe muscle weakness is hospitalized. The only abnormality in her laboratory values is an elevated serum K+ concentration. The elevated serum K+ causes muscle weakness because \nSelect and explain. \nA. The Resting Membrane Potential Is Hyperpolarized, B. The K+ Equilibrium Potential Is Hyperpolarized, C. The Na+ Equilibrium Potential Is Hyperpolarized, D. Na+ channels are closed by depolarization', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Elevated serum K+ concentration causes depolarization of the K+ equilibrium potential and therefore depolarization of the resting membrane potential in skeletal muscle. Sustained depolarization closes the Na+ channels and prevents the occurrence of action potentials in the muscle.', 'role': 'assistant'}]