This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Pharmacology
[{'content': 'Sodium nitroprusside acts by activation of \nSelect and explain. \nA. Guanylate cyclase, B. K+ chanells, C. Ca++ chanells, D. Cyclic AMP', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Nitroprusside generates NO that relaxes the vascular smooth muscle by activating Guanylate cyclase Refer kDT 6/e p548', 'role': 'assistant'}]