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
Potassium-sparing diuretics include: 
Select and explain. 
A. Amiloride, B. Triamterene, C. Spironolactone, D. Ethacrynic acid
C: Spironolactone
Answer: C: Spironolactone 
Explanation: High efficacy diuretic - Furosemide, Bumetanide, Torsemide
Medium efficacy(inhibit Na-Cl symport ) - Thiazides (Hydrochlorothiazide, Benzthiazide, Hydroflumethiazide, Clopamide), Thiazide-like (Indapamide, Xipamide, Metolazone)
Carbonic anhydrase inhibitors – Acetazolamide
Inhibitors of renal epithelial sodium channel – Triamterene, Amiloride
Potassium-sparing - Spironolactone(Aldosterone antagonist), Amiloride, Triamterene (inhibit renal epithelial Na channel)
Osmotic diuretics - Mannitol, Isosorbide, Glycerol.