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
[{'content': 'Excitable tissue at rest is least permeable to: \nSelect and explain. \nA. Na., B. K\', C. Ca", D. Cl', 'role': 'user'}, {'content': "Answer: A \nExplanation: A i.e. Na'Order of permeability in excitable tissue at rest: K+ > Cl- > Na+Q", 'role': 'assistant'}]