Pairing of homologous chromosomes into tetrads occurs during:

Options

A. interkinesis of meiosis
B. telophase of meiosis II
C. metaphase of mitosis
D. prophase of meiosis I

Answer

To solve the question regarding when the pairing of homologous chromosomes into tetrads occurs, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Process**: The pairing of homologous chromosomes is a key event in meiosis, specifically during the first division of meiosis (meiosis I).

2. **Identify the Stages of Meiosis**: Meiosis consists of two main stages: meiosis I and meiosis II. During meiosis I, homologous chromosomes pair up and exchange genetic material.

3. **Focus on Prophase I**: Within meiosis I, prophase I is divided into several sub-stages: leptotene, zygotene, pachytene, diplotene, and diakinesis. The pairing of homologous chromosomes specifically occurs during the zygotene stage.

4. **Recognize the Term Synapsis**: The process of homologous chromosomes pairing up is called synapsis, which occurs during the zygotene stage of prophase I.

5. **Evaluate the Options**:
- **A. Interkinesis of meiosis**: This is a brief phase between meiosis I and meiosis II, where no pairing occurs.
- **B. Telophase of meiosis II**: This is the final stage of meiosis II, where chromosomes are at opposite poles and are not pairing.
- **C. Metaphase of mitosis**: This is a stage of mitosis, not meiosis, and involves the alignment of chromosomes, not pairing.
- **D. Prophase of meiosis I**: This is the correct answer, as it includes the zygotene stage where synapsis occurs.

6. **Conclusion**: Based on the understanding of the stages of meiosis and the specific event of homologous chromosomes pairing, the correct answer is **D. Prophase of meiosis I**.

### Final Answer:
The pairing of homologous chromosomes into tetrads occurs during **D. Prophase of meiosis I**.