**Core Concept**
The stomach secretes various enzymes and acids to facilitate the digestion of food. This process involves the coordinated action of different cell types and glands within the stomach lining. The stomach's secretory function is crucial for protein digestion and the activation of digestive enzymes.

**Why the Correct Answer is Right**
The stomach secretes several key substances, including pepsinogens (which are converted to pepsin, a proteolytic enzyme), gastric amylase (a carbohydrate-digesting enzyme), and hydrochloric acid (HCl), which creates an acidic environment necessary for enzyme activation and protein denaturation. Lipase is also secreted by the stomach, although it is primarily responsible for triglyceride digestion. However, the stomach's primary role in lipolysis is limited compared to the pancreas and small intestine.

**Why Each Wrong Option is Incorrect**
**Option A:** Lipase is indeed secreted by the stomach, although its role is relatively minor compared to other digestive enzymes.
**Option B:** Pepsinogens are secreted by the stomach in an inactive form, which is then converted to pepsin by gastric acid, facilitating protein digestion.
**Option C:** Hydrochloric acid (HCl) is secreted by the parietal cells of the stomach lining, playing a crucial role in creating an acidic environment necessary for enzyme activation and protein denaturation.

**Clinical Pearl / High-Yield Fact**
The stomach's secretory function is regulated by the enteric nervous system and the hormone gastrin, which stimulates the secretion of gastric acid and enzymes. The stomach's digestive enzymes and acids work in concert to break down proteins, carbohydrates, and fats into smaller molecules that can be absorbed and utilized by the body.

**✓ Correct Answer: D. None**