**Core Concept**
The gastro-colic reflex is a physiological reflex that involves the stimulation of the distal colon and rectum, leading to increased motility and emptying of the stomach. This reflex is mediated by the enteric nervous system and involves the release of various neurotransmitters and hormones.

**Why the Correct Answer is Right**
The gastro-colic reflex is a normal physiological response that occurs in response to the distension of the rectum and sigmoid colon. This reflex is mediated by the release of acetylcholine from the myenteric plexus, which stimulates the smooth muscle of the stomach to contract and empty. The gastro-colic reflex is also influenced by the release of gastrin, which stimulates gastric acid secretion and gastric motility.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the gastro-colic reflex is not primarily related to the release of gastrin, although gastrin does play a role in the reflex.
**Option B:** This option is incorrect because the gastro-colic reflex is not primarily related to the release of secretin, although secretin does play a role in the regulation of gastric acid secretion.
**Option C:** This option is incorrect because the gastro-colic reflex is not primarily related to the release of cholecystokinin, although cholecystokinin does play a role in the regulation of pancreatic enzyme secretion.

**Clinical Pearl / High-Yield Fact**
The gastro-colic reflex is an important physiological reflex that helps to regulate the motility of the gastrointestinal tract. It is also an important clinical consideration in patients with gastrointestinal disorders, such as irritable bowel syndrome, where the gastro-colic reflex may be abnormal.

**Correct Answer:** C.