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
Function of M2 receptor in hea ? 
Select and explain. 
A. SA node hyperpolarisation, B. AV node increased velocity of conduction, C. Increased contractility of ventricles, D. Increased Ach release from cholinergic nerve endings
A: SA node hyperpolarisation
Answer: A: SA node hyperpolarisation 
Explanation: Ans. is 'a' i.e., SA node hyperpolarization