**Core Concept:** Meckel's diverticulum is a remnant of the omphalomesenteric duct, which is a normal embryonic structure that typically involutes (resorbs) during development. It is a tubular pouch of the gastrointestinal tract that can present clinically in adults.

**Why the Correct Answer is Right:** Meckel's diverticulum is most commonly found in the distal ileum, the lower part of the small intestine. This is because the omphalomesenteric duct typically involutes in the majority of cases, leaving only a small remnant in the ileum. In rare instances, the remnant does not involute, leading to the formation of Meckel's diverticulum.

**Why Each Wrong Option is Incorrect:**

A. Meckel's diverticulum is not typically located in the duodenum (first part of the small intestine) as it is more commonly found in the ileum.

B. The colon (large intestine) is the wrong location for Meckel's diverticulum, as it is predominantly found in the small intestine.

C. While Meckel's diverticulum can occur in the jejunum (second part of the small intestine), it is less common than in the ileum, making option D the correct answer.

D. Meckel's diverticulum is most commonly found in the distal ileum, which is the correct answer.

**Clinical Pearl:** Meckel's diverticulum is a relatively common congenital anomaly, and its presence increases the risk of complications such as gastrointestinal bleeding, intestinal obstruction, and malignant potential.

**Correct Answer:** D. Meckel's diverticulum is most commonly found in the distal ileum.