Final answer:
The mechanism involved in healing ulcers is the regeneration of the epithelial lining, which helps restore the protective barrier against gastric acid.
Step-by-step explanation:
Among the choices provided, the mechanism involved in healing ulcers is d) Regeneration of the epithelial lining. Ulcers occur when the protective mucus lining of the stomach is compromised, leading to damage of the underlying tissue. Healing of an ulcer involves regeneration of this epithelial lining to restore the barrier against gastric acid. This process is critical for maintaining the mucosal barrier, which includes a thick coating of bicarbonate-rich mucus and the replacement of damaged epithelial mucosal cells. Factors such as avoiding ingestion of substances that irritate the stomach and eliminating the bacteria Helicobacter pylori, which can decrease mucus production, are important for prevention and healing of ulcers.