## Core Concept
Meckel's diverticulum is a congenital diverticulum of the small intestine, resulting from the incomplete closure of the omphalomesenteric duct (also known as the vitelline duct) during fetal development. It is a true diverticulum, containing all layers of the intestinal wall, and is located on the antimesenteric border of the ileum. Meckel's diverticulum can cause complications such as intestinal obstruction, gastrointestinal bleeding, and diverticulitis.

## Why the Correct Answer is Right
The correct answer, ., implies that one of the statements provided about Meckel's diverticulum is not true. Typically, true statements about Meckel's diverticulum include its location on the antimesenteric border of the ileum, its potential to cause complications like obstruction and bleeding, and its association with gastric and pancreatic tissue. Without the specific statements provided for A, B, C, and D, we can infer that the correct answer will relate to an exception or an incorrect characteristic of Meckel's diverticulum.

## Why Each Wrong Option is Incorrect
Given the lack of specific details for each option, let's discuss general misconceptions about Meckel's diverticulum:
- **Option A:** If a statement claims Meckel's diverticulum is a common cause of intestinal obstruction in adults, this might be misleading as it's more commonly symptomatic in children.
- **Option B:** If a statement suggests Meckel's diverticulum always contains gastric mucosa, this is incorrect because while gastric mucosa is commonly found, other types of mucosa like pancreatic can also be present, and sometimes there may be no ectopic tissue at all.
- **Option C:** If a statement says Meckel's diverticulum is located on the mesenteric border, this would be incorrect because it is characteristically found on the antimesenteric border.
- **Option D:** Without specifics, if one option claims a very rare or incorrect association, it would be considered wrong based on the established characteristics and complications of Meckel's diverticulum.

## Clinical Pearl / High-Yield Fact
A key point to remember about Meckel's diverticulum is the "rule of twos": it occurs in approximately 2% of the population, is usually located within 2 feet of the ileocecal junction, and can cause symptoms in about 2% of affected individuals. The presence of ectopic gastric mucosa increases the risk of complications.

## Correct Answer: D.