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: Anaesthesia
[{'content': 'Ultra short acting beta blocker most commonly used in anaesthesia is – \nSelect and explain. \nA. Esmolol, B. Nadalol, C. Propanalol, D. Atenolol', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Esmolol is ultrashort acting β-blocker and is used for arrhythmias during anaesthesia.', 'role': 'assistant'}]