A physiology student is tracing the digestion of a protein-rich meal through the stomach. Which statement best explains how the stomach carries out protein digestion while avoiding damage to its own tissues?

Chief cells release pepsin, which neutralizes stomach acid while mucus dissolves food particles

Parietal cells secrete hydrochloric acid that activates pepsinogen, while mucus-producing cells create a protective lining against acid

Mucous cells secrete hydrochloric acid to digest proteins, while parietal cells release bicarbonate into the stomach lumen

Smooth muscle contractions convert proteins directly into amino acids, while chief cells prevent erosion of the stomach wall