Gestation period is the duration:

Options

A. Between egg growth and ovulation
B. Of fertilization
C. Between fertilization and parturition
D. Between preparation of sex cells and fertilisation.

Answer

**Step-by-Step Solution:**

1. **Understanding Gestation Period**: The gestation period refers to the time frame from conception to birth. It is crucial to understand this definition to answer the question accurately.

2. **Identifying Key Terms**:
- **Conception**: This occurs at fertilization, which is when the sperm and ovum unite.
- **Birth**: This refers to the moment when the fetus is delivered, also referred to as fluctuation in the transcript.

3. **Analyzing the Options**:
- **Option A**: Between egg growth and ovulation - This does not relate to gestation as it pertains to the menstrual cycle.
- **Option B**: On fertilization - This is not a duration; it is a specific event.
- **Option C**: Between fertilization and fluctuation - This correctly describes the gestation period, as it encompasses the time from fertilization to birth.
- **Option D**: Between preparation of sex cells and fertilization - This is also not the correct definition of gestation.

4. **Conclusion**: Based on the definitions and analysis of the options, the correct answer is **Option C: between fertilization and fluctuation**.

5. **Additional Information**: In humans, the average gestation period is approximately nine months.