What occurs in crossing over :

Options

A. Recombination
B. Mutation
C. Independent assortment
D. None

Answer

### Step-by-Step Solution:

1. **Understanding Crossing Over**:
- Crossing over is a biological process that occurs during meiosis, specifically during the prophase I stage. It is essential for genetic diversity.

2. **Location of Crossing Over**:
- This process takes place in the pachytene stage of prophase I of meiosis. During this stage, homologous chromosomes pair up closely.

3. **Mechanism of Crossing Over**:
- During crossing over, segments of genetic material are exchanged between non-sister chromatids of homologous chromosomes. This exchange results in a recombination of genetic material.

4. **Outcome of Crossing Over**:
- The result of crossing over is the creation of new combinations of alleles, which increases genetic variation in the gametes produced.

5. **Distinguishing from Other Processes**:
- It is important to note that crossing over is not the same as mutation. Mutation refers to changes in the DNA sequence caused by various factors, while crossing over is a natural process during gamete formation.
- Additionally, crossing over should not be confused with independent assortment, which refers to the random distribution of alleles during gamete formation.

6. **Conclusion**:
- The correct answer to the question "What occurs in crossing over?" is that it involves the recombination of genetic material between non-sister chromatids of homologous chromosomes.