Identify the stage when the bivalents are arranged at the equatorial plate with the arms of the chromatid pointing inward and centromeres pointing the poles.

Options

A. metaphase I
B. metaphase II
C. anaphase I
D. anaphase II

Answer

To identify the stage when the bivalents are arranged at the equatorial plate with the arms of the chromatids pointing inward and the centromeres pointing towards the poles, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- Bivalents refer to pairs of homologous chromosomes that are aligned together during meiosis.
- Chromatids are the two identical halves of a duplicated chromosome, joined at a region called the centromere.

2. **Identify the Arrangement**:
- The question specifies that the bivalents are arranged at the equatorial plate. This means that the chromosomes are lined up in the middle of the cell.

3. **Direction of Chromatids**:
- The arms of the chromatids are pointing inward, while the centromeres are pointing towards the poles. This arrangement is crucial for understanding the stage of cell division.

4. **Determine the Stage of Cell Division**:
- In cell division, particularly during meiosis, the arrangement of chromosomes at the equatorial plate occurs during metaphase. However, the specific description of the chromatids pointing inward and centromeres towards the poles is characteristic of **anaphase**.
- During anaphase, the sister chromatids are pulled apart towards opposite poles of the cell, resulting in the described orientation.

5. **Conclusion**:
- Therefore, the stage when the bivalents are arranged at the equatorial plate with the arms of the chromatids pointing inward and the centromeres pointing towards the poles is **Anaphase**.

### Final Answer:
The stage is **Anaphase**.