**Core Concept:** The "Rule of 2" in gastroenterology refers to the relationship between the size and number of diverticula in the large intestine. It states that the size of the diverticulum (diverticulosis) increases with age and the number increases with the degree of inflammation (diverticulitis). Mecke's diverticulum is a type of rectosigmoid diverticulum.

**Why the Correct Answer is Right:** Mecke's diverticulum, also known as rectosigmoid diverticulum, is a type of rectosigmoid diverticulum located in the rectosigmoid junction. The rule of 2 applies to colonic diverticula, which are either solitary or multiple (>2). Since Mecke's diverticulum is a solitary diverticulum, it does not follow the rule of 2.

**Why Each Wrong Option is Incorrect:**

A. False: Mecke's diverticulum is a type of rectosigmoid diverticulum, which follows the rule of 2 regarding size and number.

B. False: Mecke's diverticulum is a solitary diverticulum, thus it does not follow the rule of 2 regarding number.

C. False: Mecke's diverticulum is a type of rectosigmoid diverticulum, which is related to age and size according to the rule of 2.

D. False: Mecke's diverticulum is a type of rectosigmoid diverticulum, which does not follow the rule of 2 regarding size and number.

**Clinical Pearl:** Understanding the Rule of 2 is essential in diagnosing and managing patients with diverticular disease. The presence of multiple diverticula indicates inflammation (diverticulitis) and warrants further workup and intervention. Solitary diverticula, like Mecke's diverticulum, are usually incidental findings and do not require intervention unless complications arise.

**Correct Answer:** Diverticula that follow the rule of 2 (solitary or multiple, size and number) are considered inflammatory (diverticulitis) and require further evaluation and treatment. Mecke's diverticulum, being a solitary diverticulum, does not follow the rule of 2, making it false.