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
Which of the following drug reduces blood pressure primarily by directly decreasing heart rate alone: 
Select and explain. 
A. Propranolol, B. Prazosin, C. Alpha methyl dopa, D. Nitroprusside sodium
A: Propranolol
Answer: A: Propranolol 
Explanation: None