A. H₂ receptor antagonists (H₂RAs) do not directly address diarrhea, as their primary action is to reduce gastric acid secretion rather than influence bowel motility or consistency. B. Relief of heartburn is the primary therapeutic outcome of H₂RAs. These medications work by reducing stomach acid production, which alleviates symptoms of acid reflux and gastroesophageal reflux disease (GERD). C. H₂RAs do not have a direct effect on constipation. Constipation is more related to bowel motility, which is not influenced by the mechanism of action of these drugs. D. While the passage of flatus can indicate improved gastrointestinal function, it is not an expected therapeutic outcome of H₂RAs, as these medications target acid production rather than gas formation.