Emergency contraceptives are effective if used within

Options

A. 72 hrs after coitus
B. 72 hrs of ovulation
C. 2 hrs of menstruation
D. 72 hrs of implantation

Answer

### Step-by-Step Solution:

1. **Understanding Emergency Contraceptives**: Emergency contraceptives are methods used to prevent pregnancy after unprotected sexual intercourse. They are most commonly available in the form of oral pills.

2. **Time Frame for Effectiveness**: The effectiveness of emergency contraceptives is time-sensitive. It is crucial to understand the specific time frame within which they must be taken to prevent pregnancy.

3. **Identifying the Correct Option**: The question provides four options regarding the time frame for the effectiveness of emergency contraceptives:
- A) 72 hours after weight loss
- B) 72 hours of ovulation
- C) 72 hours of menstruation
- D) 72 hours of implantation

4. **Analyzing the Options**:
- **Option A (72 hours after weight loss)**: This option seems to be a typographical error, as it should refer to "intercourse" rather than "weight loss."
- **Option B (72 hours of ovulation)**: This option is related to the timing of ovulation, which is important, but the focus is on the time after intercourse.
- **Option C (72 hours of menstruation)**: This option does not relate to the timing of intercourse.
- **Option D (72 hours of implantation)**: This option is incorrect because implantation occurs after fertilization, and emergency contraceptives are meant to prevent fertilization.

5. **Conclusion**: The correct understanding is that emergency contraceptives are effective if used within 72 hours after unprotected sexual intercourse. Therefore, the most appropriate answer, considering the context, is **Option A** (interpreted as 72 hours after intercourse).

### Final Answer:
Emergency contraceptives are effective if used within **72 hours after unprotected intercourse**.

---