Recombination is completed by the end of

Options

A. Zygotene
B. Leptotene
C. Pachytene
D. Diplotene

Answer

### Step-by-Step Solution:

1. **Understanding Recombination**: Recombination is a process that involves the exchange of genetic material between homologous chromosomes. This process is crucial for genetic diversity and occurs during meiosis.

2. **Identifying the Stages of Meiosis**: Meiosis consists of two main stages: Meiosis I and Meiosis II. The focus here is on Meiosis I, specifically during prophase I, which is divided into five sub-stages: Leptotene, Zygotene, Pachytene, Diplotene, and Diakinesis.

3. **Analyzing the Stages of Prophase I**:
- **Leptotene**: Chromosomes begin to condense.
- **Zygotene**: Homologous chromosomes begin to pair up (synapsis).
- **Pachytene**: Crossing over occurs, where segments of DNA are exchanged between homologous chromosomes. This is where recombination is actively taking place.
- **Diplotene**: The homologous chromosomes start to separate but remain connected at the crossover points.
- **Diakinesis**: The final stage of prophase I where chromosomes condense further and prepare for metaphase.

4. **Determining When Recombination is Completed**: The question asks when recombination is completed. It is during the **Pachytene** stage that crossing over and the exchange of genetic material are fully completed.

5. **Conclusion**: Therefore, the correct answer to the question "Recombination is completed by the end of" is **Pachytene**.

### Final Answer:
Recombination is completed by the end of **Pachytene**.

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