This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Acute coronary syndrome, Subject name: Medicine
Which drug prolongs life in a patient with chronic stable angina? 
Select and explain. 
A. Aspirin, B. Beta Blocker, C. CCB, D. ACE inhibitor
B: Beta Blocker
Answer: B: Beta Blocker 
Explanation: Due to oxygen conservation capability, beta blockers have been proved to reduce moality in CSA. Multiple RCT have shown benefit of beta blockers