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
Mechanism of action of beta-blockers in glaucoma is 
Select and explain. 
A. Increases uveo-scleral out flow of aqueous, B. Increases trabecular mesh work out flow, C. Decreaes aqueous production, D. Constant aqueous production in ciliary body
C: Decreaes aqueous production
Answer: C: Decreaes aqueous production 
Explanation: (Decreases aquous formation): Ref: 222-KH, 87-KDTMechanism of actions of beta-adrenergic blockersTimolol and levobunolal are non selective beta 1 (Cardiac) and beta 2 (smooth muscle, pulmonary) receptor blockers, causes lower IOP by blockade of beta - 2 rceptors in the ciliary process resulting in decreased aquous production.* Betaxolol are thought to increase the perfusion of the optic nerve head (305-P) cardio selective* Metipranolol: only in preservative free units, it is therefore useful in patients allergic to preservatives or wearing soft contact lens (in whom benzolkonium chloride should be avoided)Mode of action of ocular hypotensive drugs (87-KDT)Drugs/classAqueous secretionTrabecular outflowUveoscleral outflow1. b-blockers (Timolol)|----2. Miotics (Pilocarpine)--|--3. Adrenal ine/Dipi ve fri ne|?||4. Brimonidine/Apraclonidine|--|?5. Prostaglandins (latanoprost--|?|6. Carbonic anhydrase inhibitors|----