**Core Concept**
Gastric secretion refers to the process by which the stomach produces and releases digestive enzymes and acids to break down food. This process is regulated by **hormonal** and **nervous** mechanisms. The **gastric glands** play a crucial role in this process.

**Why the Correct Answer is Right**
The correct answer is related to the regulation of gastric secretion, which involves **gastrin**, a hormone released by **G cells** in the stomach. Gastrin stimulates the **parietal cells** to release **hydrochloric acid** and the **chief cells** to release **pepsinogen**.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because it does not accurately describe the primary mechanism of gastric secretion.
**Option B:** Incorrect as it is not directly related to the regulation of gastric secretion.
**Option C:** Incorrect because it is not the primary hormone involved in stimulating gastric secretion.
**Option D:** Incorrect as it is not a key player in the regulation of gastric secretion.

**Clinical Pearl / High-Yield Fact**
Gastric secretion is a critical process in digestion, and its dysregulation can lead to various **gastrointestinal disorders**. Understanding the mechanisms of gastric secretion is essential for managing conditions like **peptic ulcer disease**.

**Correct Answer:** D. Stimulated by gastrin, secreted by G cells, and inhibited by secretin and gastric inhibitory peptide, with a pH of 1.5-3.5.