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': 'Which of the following drugs has been used in the treatment of angina by inhalation and has a very rapid onset and brief duration of action ? \nSelect and explain. \nA. Amyl nitrite, B. Isosorbide mononitrate, C. Nitroglycerine, D. Propranolol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]