Emergency contraceptives are effective if used within

Options

A. 72 hrs of coitus.
B. 72 hrs of ovulation.
C. 72 hrs of menstruation.
D. 72 hrs of implantation.

Explanation

**Step-by-Step Solution:**

1. **Understanding Emergency Contraceptives**: Emergency contraceptives are methods used to prevent pregnancy after unprotected sexual intercourse or contraceptive failure.

2. **Time Frame for Effectiveness**: The effectiveness of emergency contraceptives is highly dependent on the timing of administration. They are most effective when taken as soon as possible after unprotected intercourse.

3. **Evaluating the Options**:
- **Option A**: 72 hours of coitus - This suggests taking the emergency contraceptive within 72 hours after unprotected sex.
- **Option B**: 72 hours of ovulation - This refers to the time after ovulation, which is not the correct timing for taking emergency contraceptives.
- **Option C**: 72 hours of menstruation - This does not relate to the effectiveness of emergency contraceptives.
- **Option D**: 72 hours of implantation - This is too late for emergency contraceptives to be effective, as they work to prevent fertilization or implantation.

4. **Conclusion**: Based on the evaluation, the correct answer is **Option A: 72 hours of coitus**. Emergency contraceptives should be taken within 72 hours after unprotected sexual intercourse to be effective.

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