**Core Concept**
The stomach contains various enzymes that break down food proteins into smaller peptides and amino acids. The primary mechanism of protein degradation in the stomach involves an enzyme that cleaves peptide bonds, releasing free amino acids.

**Why the Correct Answer is Right**
The enzyme primarily responsible for protein degradation in the stomach is pepsin. Pepsin is a gastric protease that hydrolyzes peptide bonds between amino acids, resulting in the formation of smaller peptides and free amino acids. Pepsin is secreted by chief cells in the stomach lining in its inactive form, pepsinogen, which is converted to its active form by the acidic environment of the stomach.

**Why Each Wrong Option is Incorrect**
* **Option A:** Gastric amylase is involved in breaking down starches into sugars, not proteins.
* **Option B:** Gastric lipase is involved in breaking down fats into fatty acids and glycerol, not proteins.
* **Option C:** Trypsin is a pancreatic protease that breaks down proteins into smaller peptides, but it is not the primary enzyme responsible for protein degradation in the stomach.

**Clinical Pearl / High-Yield Fact**
Pepsin is an enzyme that is highly susceptible to denaturation by heat and pH changes, which is why it is inactivated by antacids and acid-reducing medications.

**Correct Answer: C. Trypsin**