This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Gastrointestinal tract, Subject name: Pharmacology
A patient presents with zo11inger-Ellison syndrome due to gastrinoma. He has two bleeding ulcers and diarrhoea. A drug that irreversibly inhibits the H+/K+ ATPase in gastric parietal cells is: 
Select and explain. 
A. Cimetidine, B. Cisapride, C. Glycopyrrolate, D. Omeprazole
D: Omeprazole
Answer: D: Omeprazole 
Explanation: that react covalently with SH groups of the H+K+ATP ase enzyme and inactivate it irreversibly ESSENTIALS OF MEDICAL PHARMACOLOGY SEVENTH EDITION KD TRIPATHI PG NO 651