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: Pharmacology
[{'content': 'Function of M2 receptor in hea ? \nSelect and explain. \nA. SA node hyperpolarisation, B. AV node increased velocity of conduction, C. Increased contractility of ventricles, D. Increased Ach release from cholinergic nerve endings', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., SA node hyperpolarization", 'role': 'assistant'}]