Disjunction is
(a) Chromosome separation during mitosis
(b) Chromosome separation during prophase I
(c) Chromosome separation in anaphase I
(d) Chromosome separation during metaphase I

Options

A. Chromosome separation during mitosis
B. Chromosome separation during prophase I
C. Chromosome separation in anaphase I
D. Chromosome separation during metaphase I

Answer

To solve the question regarding disjunction, we need to understand the concept of disjunction in the context of cell division, specifically meiosis.

### Step-by-Step Solution:

1. **Understanding Disjunction**: Disjunction refers to the separation of homologous chromosomes during cell division. This process is crucial for ensuring that gametes receive the correct number of chromosomes.

2. **Identifying the Stages of Meiosis**: Meiosis consists of two main stages: Meiosis I and Meiosis II. In Meiosis I, homologous chromosomes are separated, while in Meiosis II, sister chromatids are separated.

3. **Analyzing the Options**:
- **Option (a)**: Chromosome separation during mitosis - This is incorrect as mitosis involves the separation of sister chromatids, not homologous chromosomes.
- **Option (b)**: Chromosome separation during prophase I - This is incorrect; prophase I is when homologous chromosomes pair up, not separate.
- **Option (c)**: Chromosome separation in anaphase I - This is correct as disjunction occurs during anaphase I when homologous chromosomes are pulled apart to opposite poles.
- **Option (d)**: Chromosome separation during metaphase I - This is incorrect; metaphase I is when homologous chromosomes align at the metaphase plate, not separate.

4. **Conclusion**: Based on the understanding of disjunction and the analysis of the options, the correct answer is:
- **(c) Chromosome separation in anaphase I**.