Assertion : Presence of zona pallucida over the fertilized ovum prevents ectopic pregnancy .
Reason : Zona pellucida helps the ovum to penetrate endometrium .

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion .
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False .
D. If both Assertion & Reason are False.

Answer

### Step-by-Step Solution:

1. **Understanding Ectopic Pregnancy**:
- Ectopic pregnancy occurs when a fertilized egg implants outside the uterus, commonly in the fallopian tubes or abdominal cavity. This type of pregnancy cannot develop normally and is often terminated.

2. **Analyzing the Assertion**:
- The assertion states that the presence of zona pellucida over the fertilized ovum prevents ectopic pregnancy.
- Zona pellucida is a glycoprotein layer surrounding the ovum that plays a crucial role in fertilization and prevents multiple sperm from fertilizing the same ovum.

3. **Evaluating the Reason**:
- The reason given is that zona pellucida helps the ovum to penetrate the endometrium.
- However, the primary function of zona pellucida is to facilitate sperm binding and prevent polyspermy (multiple sperm fertilizing the ovum). It does not directly assist in the implantation of the ovum into the endometrium.

4. **Conclusion**:
- The assertion is true as the zona pellucida does play a role in preventing ectopic pregnancies by ensuring proper fertilization.
- The reason is false because zona pellucida does not assist in the penetration of the endometrium; that process is facilitated by other factors once the fertilized ovum is ready to implant.

5. **Final Answer**:
- Therefore, the correct answer is that the assertion is true, but the reason is false.