## **Core Concept**
The question revolves around emergency contraception, which is a method used to prevent pregnancy after unprotected sex or contraceptive failure. The goal is to find a suitable single-dose postcoital contraceptive that can be administered to Shagun.

## **Why the Correct Answer is Right**
Levonorgestrel (Option C) is a synthetic progestogen that can be used as emergency contraception to prevent pregnancy when taken as a single dose or in two doses 12 hours apart. It works by inhibiting or delaying ovulation, and it may also affect the endometrium, making it less receptive to implantation of a fertilized egg. The recommended dose for emergency contraception is 1.5 mg as a single dose or 0.75 mg taken twice, 12 hours apart. Given that Shagun had intercourse 5 hours ago, a single dose of Levonorgestrel can be effective.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While Mifepristone is used for medical abortion and can act as an emergency contraceptive, it is not typically administered as a single dose for postcoital contraception in the same way Levonorgestrel is. Its use for emergency contraception involves a single dose but is less commonly chosen compared to Levonorgestrel due to its different primary indication.
- **Option B:** This option seems to be a distractor as no specific drug is mentioned, making it impossible to evaluate its correctness.
- **Option D:** Ulipristal acetate is another medication used for emergency contraception. However, it is typically given as a single dose of 30 mg and is considered when Levonorgestrel cannot be used or is not available. It is effective up to 120 hours after unprotected sex, but Levonorgestrel remains a more commonly recommended first-line option within the specified time frame.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that for emergency contraception to be most effective, it should be initiated as soon as possible after unprotected intercourse, ideally within 72 hours. Levonorgestrel (1.5 mg single dose) and Ulipristal acetate (30 mg single dose) are both effective options, but their effectiveness slightly decreases with increasing time since exposure.

## **Correct Answer:** C. Levonorgestrel.