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': 'Alpha 2 agonist used in glaucoma is ? \nSelect and explain. \nA. Brimonidine, B. Timolol, C. Phenylephrine, D. Reserpine', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Brimonidine", 'role': 'assistant'}]