This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Kidney, Subject name: Pharmacology
Acetazolamide is: 
Select and explain. 
A. Competitive and reversible carbonic anhydrase inhibitor, B. Non-competitive and reversible carbonic anhydrase inhibitor, C. Competitive and irreversible carbonic anhydrase inhibitor, D. Non-competitive and irreversible carbonic anhydrase inhibitor
B: Non-competitive and reversible carbonic anhydrase inhibitor
Answer: B: Non-competitive and reversible carbonic anhydrase inhibitor 
Explanation: It is a sulfonamide derivative which noncompetitively but reversibly inhibits carbonic anhydrase in PT cells resulting in slowing of hydration of Carbon dioxide and leads to prompt but mild alkaline diuresis. The extrarenal actions of acetazolamide are: i) Lowering of intraocular tension due to decreased formation of aqueous humor (it is rich in HC03). ii) Decreased gastric HCl and pancreatic NaHC03 secretion: This action requires very high doses-clinically not significant. iii) Raised level of C02 in the brain and lowering of pH - sedation and elevation of seizure threshold. iv) Alteration of C02 transpo in lungs and tissues: these actions are masked by compensatory mechanisms. REF-Essentials of Medical Pharmacology, K.D Tripathi,6 th edition, page 569