**Question:** True about endometriosis:

A. It is a condition where endometrial tissue grows outside the uterus.
B. It commonly affects women of reproductive age.
C. It mainly presents with gastrointestinal symptoms.
D. Endometriosis is not associated with pelvic pain.

**Correct Answer:** B. It commonly affects women of reproductive age.

**Core Concept:** Endometriosis is a chronic inflammatory condition characterized by the presence of endometrial-like tissue outside the uterus. This tissue exhibits cyclic changes in response to hormonal influences, leading to symptoms and complications.

**Why the Correct Answer is Right:** Endometriosis primarily affects women during their reproductive years as the hormonal changes that occur during menstruation and pregnancy promote the growth and regression of endometrial tissue. When endometrial tissue is implanted outside the uterus, it can cause pain, infertility, and other complications.

**Why Each Wrong Option is Incorrect:**

A. While endometriosis does involve endometrial tissue outside the uterus, the focus of the question is on the age group affected. This option is partially correct but does not address the main point.

C. Gastrointestinal symptoms are seen in some cases of endometriosis, but pelvic pain is the primary symptom affecting the majority of patients. This option is partially correct but does not address the main point regarding age group.

D. The statement that endometriosis is not associated with pelvic pain is incorrect, as pelvic pain is a hallmark symptom of the condition. This option is incorrect and does not address the main point regarding age group.

**Clinical Pearl:** Understanding the age group affected by endometriosis is crucial in making an accurate diagnosis and providing appropriate treatment options for patients. Early identification and management can lead to better outcomes and quality of life for women with endometriosis.