**Core Concept**
Endometriosis is a complex and multifactorial disorder characterized by the growth of endometrial tissue outside the uterus, leading to chronic inflammation, scarring, and adhesions. The etiology of endometriosis involves a combination of genetic, hormonal, and environmental factors.

**Why the Correct Answer is Right**
The exact cause of endometriosis is still not fully understood, but it is believed to involve a combination of genetic predisposition, hormonal influences, and environmental factors such as retrograde menstruation. The hormonal theory suggests that estrogen promotes the growth of endometrial tissue, while progesterone inhibits it. In endometriosis, the balance between estrogen and progesterone is disrupted, leading to unopposed estrogen stimulation of endometrial tissue growth.

**Why Each Wrong Option is Incorrect**
**Option A:** Coelomic metaplasia is a proposed mechanism of endometriosis etiology, but it is not a proven theory and is considered less likely to be the primary cause. **Option B:** Immune system dysfunction is thought to play a role in the development of endometriosis, but it is not a direct cause of the condition. **Option C:** Infection is not a recognized cause of endometriosis.

**Clinical Pearl / High-Yield Fact**
Endometriosis is a leading cause of chronic pelvic pain and infertility in women of reproductive age. It is essential to consider endometriosis in the differential diagnosis of women with pelvic pain, dysmenorrhea, and infertility.

**Correct Answer: C. Infection is not a recognized cause of endometriosis.**