This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastro-Intestinal Tract, Subject name: Pharmacology
Prompt pump inhibitor suppress gastric acid secretion by acting on: 
Select and explain. 
A. H+/ Cl- ATPase pump, B. H+/ K+ ATPase pump, C. Na+ / K+ ATPase pump, D. Na+ / K+ /Cl-ATPase pump
B: H+/ K+ ATPase pump
Answer: B: H+/ K+ ATPase pump 
Explanation: PPIs(proton pump inhibitor): - Irreversible inhibitors- Example of HIT and RUN drugs- Exes systemic effect: normally acid labile, given with acid resistant coating.- DOC for: PUD, GERD, Zollinger Ellison syndrome- Prompt pump inhibitor suppress gastric acid secretion by acting on H+/K+ pump. Side effect: (chronic use): - Osteoporosis(decrease calcium)- Megaloblastic anemia(decrease vitamin B12)- Infection