In the production of test tube baby

Options

A. Fertilization is external and foetus formation is internal
B. fertilization is internal and foetus formation is external
C. fertilization and foetus formation are external
D. Fertilization and foetus formation are internal

Answer

### Step-by-Step Solution:

1. **Understanding Test Tube Baby**:
- A test tube baby refers to a baby conceived through a method called In Vitro Fertilization (IVF), which is used by couples who are unable to conceive naturally.

2. **Natural Conception**:
- In natural conception, fertilization occurs when a male sperm fertilizes a female egg inside the female's uterus after sexual intercourse.

3. **In Vitro Fertilization (IVF)**:
- In IVF, the male sperm and female egg are collected and fertilized outside the body, in a laboratory setting. This process is referred to as external fertilization.

4. **Formation of Zygote**:
- Once the sperm fertilizes the egg in the lab, a zygote is formed. This zygote is then cultured for a few days until it develops into an embryo.

5. **Transfer to Uterus**:
- The developed embryo (or zygote) is then transferred into the uterus of the female partner, where it will implant and develop into a fetus.

6. **Fetus Formation**:
- The development of the fetus occurs internally within the uterus of the female partner after the embryo has been implanted.

7. **Conclusion**:
- Therefore, in the production of a test tube baby, fertilization occurs externally (in the lab), while the formation of the fetus occurs internally (in the uterus).

### Final Answer:
- The correct option is: **Fertilization is external and fetus formation is internal.** (Option A)

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