This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'The pacemaker of hea is: \nSelect and explain. \nA. SA node, B. AV node, C. Both, D. None', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The primary pacemaker of hea is SA node. It shows restless membrane potential similar to Interstitial cells of cajal,Pre-botzinger complex Ref:Guyton and Hall textbook of medical physiology 12th edition,page number:177', 'role': 'assistant'}]