**Core Concept**
The gastro-colic reflex is a physiological reflex that involves the contraction of the colon in response to the presence of food in the stomach. This reflex is mediated by the enteric nervous system and is a key component of the gut-brain axis. The gastro-colic reflex helps to coordinate the movement of food through the gastrointestinal tract.

**Why the Correct Answer is Right**
The gastro-colic reflex is triggered by the release of gastrin and cholecystokinin (CCK) in the stomach, which stimulates the release of acetylcholine from the enteric nervous system. Acetylcholine then acts on the smooth muscle of the colon to induce contractions, helping to move feces through the colon and into the rectum for defecation. This reflex is an important mechanism for maintaining regular bowel movements and preventing constipation.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the gastro-colic reflex is not related to the release of insulin in the pancreas. While insulin does play a role in glucose metabolism, it is not involved in the gastro-colic reflex.
**Option B:** This option is incorrect because the gastro-ileal reflex is a different physiological reflex that involves the release of hormones in the ileum to stimulate the release of bile and pancreatic juice into the small intestine. It is not related to the gastro-colic reflex.
**Option C:** This option is incorrect because the gastro-gastric reflex is a different physiological reflex that involves the release of gastrin in the stomach to stimulate the release of gastric acid. It is not related to the gastro-colic reflex.

**Clinical Pearl / High-Yield Fact**
The gastro-colic reflex is an important mechanism for maintaining regular bowel movements, and its disruption can lead to constipation or other gastrointestinal disorders. Patients with conditions such as irritable bowel syndrome (IBS) may experience altered gut motility and a disrupted gastro-colic reflex.

**Correct Answer: C. Gastro-ileal reflex**