This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anatomy
[{'content': 'The pacemaker potential is due to \nSelect and explain. \nA. Fast Na+ channel, B. Decrease in K+ permeability, C. Slow Ca++ channel, D. Rapid repolarization', 'role': 'user'}, {'content': 'Answer: B \nExplanation: .', 'role': 'assistant'}]