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': 'G protein coupled receptor ? \nSelect and explain. \nA. NMDA receptor, B. Steroid, C. M2, D. Insulin receptors', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., M2M2 muscarinic receptors are G-protein coupled receptors and act through cAMP.", 'role': 'assistant'}]