This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pharmacology
[{'content': 'Which of the following drug reduces blood pressure primarily by directly decreasing heart rate alone? \nSelect and explain. \nA. Propranolol, B. Prazosin, C. Alpha methyl dopa, D. Nitroprusside sodium', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (A) Propranolol(Ref: Katzung 10/e p165, 169; KDT 8th/e p158)*Methyldopa is useful in the treatment of mild to moderately severe hypertension. It lowers blood pressure chiefly by reducing peripheral vascular resistance, with a variable reduction in heart rate and cardiac output.*Prazosin and nitroprusside are vasodilators and produce reflex tachycardia instead of causing bradycardia.*Propranolol is a non selective beta blocker and acts mainly by decreasing heart rate.', 'role': 'assistant'}]