Separation of the homologous chromosome of a pair occurs during

Options

A. Congression
B. Disjunction
C. Bivalent formation
D. Synapsis

Answer

To solve the question regarding the separation of homologous chromosomes, we will analyze the options provided and determine which one correctly describes the process.

### Step-by-Step Solution:

1. **Understanding Homologous Chromosomes**:
- Homologous chromosomes are pairs of chromosomes that have the same structure and carry the same genes, but may have different alleles. They are crucial during cell division, particularly meiosis.

2. **Identifying the Process of Separation**:
- The question asks specifically about the separation of homologous chromosomes. This separation is a key event in meiosis, particularly during the first meiotic division.

3. **Evaluating the Options**:
- **Option A: Congression**: This term refers to the alignment of chromosomes at the metaphase plate during cell division. It does not involve the separation of homologous chromosomes.
- **Option B: Disjunction**: This term refers to the process where homologous chromosomes (or sister chromatids) are pulled apart and move to opposite poles of the cell during anaphase. This is indeed the correct process for the separation of homologous chromosomes.
- **Option C: Bivalent Formation**: This occurs during prophase I of meiosis when homologous chromosomes pair up to form bivalents (or tetrads). This is not the separation process.
- **Option D: Synapsis**: This is the process where homologous chromosomes pair closely together during prophase I of meiosis. It is also not related to the separation of chromosomes.

4. **Conclusion**:
- After evaluating all options, the correct answer is **Option B: Disjunction**, as it specifically refers to the separation of homologous chromosomes during cell division.

### Final Answer:
The separation of the homologous chromosome of a pair occurs during **disjunction**.