**Core Concept**
Omeprazole is a proton pump inhibitor (PPI) that reduces gastric acid secretion by inhibiting the H+/K+ ATPase enzyme system in the gastric parietal cells. This mechanism is crucial in treating conditions like gastroesophageal reflux disease (GERD), peptic ulcers, and Zollinger-Ellison syndrome.

**Why the Correct Answer is Right**
Omeprazole works by irreversibly binding to the H+/K+ ATPase enzyme system on the gastric parietal cell surface, effectively reducing the secretion of hydrochloric acid in the stomach. This inhibition is achieved through the formation of a covalent bond between the sulfene intermediate of omeprazole and the cysteine residue of the H+/K+ ATPase enzyme. This leads to a significant decrease in gastric acid production, alleviating symptoms associated with excessive acid secretion.

**Why Each Wrong Option is Incorrect**
**Option A:** Omeprazole's primary mechanism is not through the inhibition of histamine H2 receptors, which is a characteristic of H2 receptor antagonists like ranitidine.
**Option B:** Omeprazole does not work by stimulating the release of gastrin, a hormone that increases gastric acid secretion.
**Option C:** Omeprazole's effects are not primarily due to its antisecretory action on the pancreas, which is more relevant to the mechanism of action of somatostatin analogs.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that PPIs like omeprazole have a delayed onset of action due to the time required for the enzyme inhibition to occur, typically taking 1-3 days to reach full effect.

**Correct Answer: C. Omeprazole's effects are due to its irreversible inhibition of the H+/K+ ATPase enzyme system on the gastric parietal cell surface.**