This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Sympathetic System, Subject name: Pharmacology
[{'content': 'Agonistic action at which of the following adrenergic receptors results in the reduction of aqueous secretion? \nSelect and explain. \nA. b1 receptor, B. b2 receptor, C. M2 receptor, D. a2 receptor', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Stimulation of a2 receptors located on ciliary epithelium reduces secretion of aqueous humor. They are useful in glaucoma as they reduce the i.o.t a2 agonists used in glaucoma are : Apraclonidine and Brominidine', 'role': 'assistant'}]