**Core Concept**
Danazol is a synthetic steroid with androgenic and anti-estrogenic properties, used primarily in the treatment of conditions related to hormonal imbalance.

**Why the Correct Answer is Right**
Danazol is used in the treatment of endometriosis, a condition characterized by the growth of endometrial tissue outside the uterus. The androgenic properties of danazol lead to a decrease in estrogen levels by inhibiting the production of gonadotropins, thereby reducing the growth of endometrial tissue. Additionally, danazol's anti-estrogenic effects help to reduce the growth of fibrocystic breast tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** Danazol is not used in the treatment of hypertension. While some steroids may have effects on blood pressure, danazol is not a primary treatment for hypertension.
**Option B:** Danazol is not used in the treatment of peptic ulcer disease. While some medications may have effects on gastric acid secretion, danazol is not a treatment for peptic ulcer disease.
**Option C:** Danazol is not used in the treatment of asthma. While some medications may have effects on airway constriction, danazol is not a treatment for asthma.

**Clinical Pearl / High-Yield Fact**
Danazol can cause significant changes in lipid profiles, including increased levels of LDL cholesterol and triglycerides, which should be monitored in patients taking this medication.

**Correct Answer: C. Endometriosis. Danazol is used in the treatment of endometriosis.**