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': 'Pacemaker potential occurs due to \nSelect and explain. \nA. Opening of transient, rapid T-type Ca2+ channel, B. Opening of K+ channel, C. Closure of Ca2+ channel, D. Closure of funny Na+  channel', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Pacemaker potential occurs due to\n\nOpening of slow type funny Na+\xa0channel\nOpening of transient, rapid T-type Ca2+\xa0channel\nEarly closure of K+\xa0channel', 'role': 'assistant'}]