This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Drugs for Peptic Ulcer, Subject name: Pharmacology
The most efficacious drug for inhibiting round the clock gastric acid output is: 
Select and explain. 
A. Omeprazole, B. Cimetidine, C. Pirenzepine, D. Misoprostol
A: Omeprazole
Answer: A: Omeprazole 
Explanation: -PPI like omeprazole are strongest acid inhibitors. -PPI are drug of choice for peptic ulcer.