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
[{'content': 'Drug of choice for classical angina attack ? \nSelect and explain. \nA. CCBs, B. b-blocker, C. GTN, D. Prazocin', 'role': 'user'}, {'content': "Answer: C \nExplanation: Ans. is 'c' i.e., GTN For immediate pre-exeional prophylaxis and acute attack Sublingual glyceral trinitrate (Drug of choice)", 'role': 'assistant'}]