Which class of acid-controlling drugs work by raising the pH of the stomach causing it to become more neutral?

A. Proton pump inhibitors: Proton pump inhibitors suppress gastric acid secretion by irreversibly inhibiting the hydrogen–potassium ATPase pump in parietal cells. This reduces acid production over time rather than directly neutralizing existing gastric acid. Their effect is delayed and mechanism is not pH neutralization. B. Histamine 2 receptor antagonists: H2 receptor antagonists decrease acid secretion by blocking histamine-mediated stimulation of parietal cells. They lower the volume and concentration of gastric acid but do not neutralize acid already present. The stomach pH rises indirectly through reduced secretion. C. Antacids: Antacids contain alkaline substances that chemically neutralize existing hydrochloric acid in the stomach. This immediate buffering action raises gastric pH and reduces acidity. They provide rapid symptomatic relief by making the gastric environment more neutral. D. Ondansetron: Ondansetron is a serotonin (5-HT3) receptor antagonist used to prevent nausea and vomiting. It does not affect gastric acid secretion or pH. Its action is unrelated to acid control.