**Core Concept**
Emergency contraception refers to the use of medications or devices to prevent pregnancy after unprotected intercourse. This can be achieved through various methods, including hormonal contraceptives and non-hormonal options like the copper IUCD.

**Why the Correct Answer is Right**
All the listed options can be used as emergency contraception if administered within a specific time frame after unprotected intercourse. **Mifepristone** is a progesterone receptor antagonist that inhibits ovulation and also has a direct effect on the endometrium. **Progesterone-only pills (POPs)** can prevent ovulation or fertilization by creating an unfavorable uterine environment. **Combined oral contraceptives (COCs)** contain both estrogen and progesterone, which also prevent ovulation by suppressing the pituitary-ovarian axis. The **copper IUCD**, when inserted within 5 days of unprotected intercourse, creates a toxic environment for sperm, preventing fertilization. **Mifepristone** can be used up to 120 hours (5 days) after intercourse, **COCs** within 72 hours, and **Progesterone-only pills** within 72 hours.

**Why Each Wrong Option is Incorrect**
**Option A:** The copper IUCD is only effective if inserted within 5 days of unprotected intercourse, not within 3 days.

**Option B:** While both mifepristone and COCs can be used as emergency contraceptives, progesterone-only pills are generally less effective and not recommended as a standalone method.

**Option C:** Mifepristone is not the only option available; all the listed methods can be used as emergency contraception within the specified time frame.

**Clinical Pearl / High-Yield Fact**
Emergency contraception can be highly effective if initiated within a short time frame after unprotected intercourse, with the copper IUCD being the most effective option when inserted within 5 days. It's essential to counsel patients on the available options and their effectiveness.

**✓ Correct Answer: D. All of these can work if used within 3 days of Unprotected Intercourse**