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': 'Nonselective beta adrenergic antagonist is \nSelect and explain. \nA. Nodalol, B. Atenolol, C. Bisoprolol, D. Esmolol', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Nodalol", 'role': 'assistant'}]