## **Core Concept**
The question tests knowledge on emergency contraception, specifically the dosing regimen of Levonorgestrel, a synthetic progestin used to prevent pregnancy after unprotected sex.

## **Why the Correct Answer is Right**
Levonorgestrel for emergency contraception is given in a total dose of 1.5 mg, which can be administered as a single dose of 1.5 mg or as two doses of 0.75 mg, 12 hours apart. This regimen has been shown to be effective in preventing pregnancy when used within 72 hours of unprotected sex.

## **Why Each Wrong Option is Incorrect**
- **Option A:** 0.75 mg is a partial dose; it's half of the total dose required for emergency contraception.
- **Option B:** 3.0 mg is double the recommended dose; higher doses are not necessary and may increase side effects without added benefit.
- **Option C:** 2.0 mg is also not a standard dosing regimen for Levonorgestrel in emergency contraception.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that Levonorgestrel works best when used as soon as possible after unprotected sex, with efficacy decreasing over time but still offering some protection up to 120 hours. It's also important to note that Levonorgestrel does not terminate an existing pregnancy.

## **Correct Answer:** D. 1.5 mg.