The first sign of the second month foetus may noticed by listening to the heart sound carefully through the stethoscope . Embryo heart is formed _____.

Options

A. By the end of the second month of pregnancy
B. By the end of first trimester
C. After one month of pregnancy
D. During fifth month

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks when the embryo's heart is formed, given that the first sign of a fetus in the second month can be detected by listening to the heart sound through a stethoscope.

2. **Gestation Period Overview**: The human gestation period is divided into three trimesters:
- First trimester: Month 1 to 3
- Second trimester: Month 4 to 6
- Third trimester: Month 7 to 9

3. **Development of the Heart**: The heart is one of the first organs to develop in an embryo. It begins to form early in the pregnancy.

4. **Timing of Heart Formation**: By the end of the first month of pregnancy (approximately 4 weeks), the heart of the embryo is formed. This means that the heart can start beating and can be detected.

5. **Detection of Heart Sound**: By the end of the second month (approximately 8 weeks), the heart sounds can be heard using a stethoscope, indicating the embryo's heart is functioning.

6. **Conclusion**: Therefore, the embryo's heart is formed after the first month of pregnancy, which corresponds to the end of the first trimester.

7. **Final Answer**: The correct answer is that the embryo's heart is formed after the first month of pregnancy.

---