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': 'Most diffusable ion in excitable tissue is : \nSelect and explain. \nA. Na., B. K., C. PO4, D. Cl', 'role': 'user'}, {'content': 'Answer: B \nExplanation: B i.e. K+ potassium ion is most diffusible ion', 'role': 'assistant'}]