**Core Concept**
Emergency contraception refers to the use of medications or devices to prevent pregnancy after unprotected sex or contraceptive failure. The goal is to delay or inhibit ovulation, prevent fertilization, or prevent implantation of a fertilized egg. Various methods and medications are employed for emergency contraception.

**Why the Correct Answer is Right**
Danazol is a synthetic steroid with antigonadotropic properties, primarily used in the treatment of endometriosis and fibrocystic breast disease. It is not typically used for emergency contraception. In contrast, the other options are all viable methods for emergency contraception. Mifepristone, a progesterone receptor antagonist, works by delaying ovulation and preventing implantation. IUCD (Intrauterine Contraceptive Device), specifically the copper IUD, creates an inflammatory reaction in the uterus, making it inhospitable for implantation. Levonorgestrel, a progesterone-only pill, inhibits ovulation and prevents fertilization.

**Why Each Wrong Option is Incorrect**
**Option A:** Mifepristone is actually used for emergency contraception, as it delays ovulation and prevents implantation.
**Option B:** IUCD is a recognized method of emergency contraception, particularly effective when inserted within 5-7 days of unprotected sex.
**Option C:** Levonorgestrel is widely used for emergency contraception, available in the form of Plan B or other generic brands.

**Clinical Pearl / High-Yield Fact**
It's essential to note that emergency contraception is most effective when used within 72 hours of unprotected sex. The use of IUCD for emergency contraception can be effective up to 5-7 days post-exposure, but levonorgestrel and mifepristone are most effective within the first 24-48 hours.

**✓ Correct Answer: D. Danazol. Danazol is not used for emergency contraception.**