**Core Concept**
Meckel's diverticulum is a congenital anomaly of the small intestine, characterized by a true diverticulum of the ileum containing a remnant of the omphalomesenteric duct. It is a vestigial structure that remains after the normal closure of the duct during fetal development.

**Why the Correct Answer is Right**
Meckel's diverticulum typically presents with a few distinct features, including:
- A true diverticulum of the ileum, which is a pouch-like protrusion of the intestinal wall.
- A remnant of the omphalomesenteric duct, which is usually a fibrous cord or a small, sometimes functioning, gastric or pancreatic tissue.
- A location near the junction of the ileum and the cecum.
- A size ranging from a few millimeters to several centimeters.
- A potential for complications such as intestinal obstruction, bleeding, or diverticulitis.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not a feature of Meckel's diverticulum.
Meckel's diverticulum is typically located in the ileum, not in the jejunum, which is a different part of the small intestine.

**Option B:** This option is not a feature of Meckel's diverticulum.
Although Meckel's diverticulum may contain ectopic tissue, it is not typically associated with a significant amount of lymphoid tissue, which is more characteristic of the appendix.

**Option C:** This option is not a feature of Meckel's diverticulum.
Meckel's diverticulum is a congenital anomaly and is not typically associated with acquired conditions such as Crohn's disease or ulcerative colitis.

**Option D:** This option is not a feature of Meckel's diverticulum.
Meckel's diverticulum is a true diverticulum, which means that it contains all layers of the intestinal wall, whereas a false diverticulum would only contain mucosa and submucosa.

**Clinical Pearl / High-Yield Fact**
Meckel's diverticulum is a common congenital anomaly, with an incidence of approximately 2% of the population. It is often asymptomatic but can cause complications such as intestinal obstruction or bleeding, especially in children.

**Correct Answer:** A.