This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Glaucoma, Subject name: Ophthalmology
[{'content': 'A patient came to the casualty with acute attack of asthma after starting treatment of glaucoma. The causative drug is \nSelect and explain. \nA. Timolol, B. Betaxolol, C. Clonidine, D. Acetazolamide', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Timolol(Ref: Kanski 7/e, p. 383; Katzung 12/e, p. 158)Timolol is a non-selective beta blocker and thus acts on Beta 2 receptors also, leading to broncospasm and exacerbation of asthmaBetaxolol is a cardioselective (beta 1 blocker) and thus is free from this side effect', 'role': 'assistant'}]