Duplication of centriole in animal cells occurs during

Options

A. `G_(1)` -phase
B. S-phase
C. `G_(2)` -phase
D. `G_(0)` -phase

Answer

**Step-by-Step Solution:**

1. **Understanding the Cell Cycle**: The cell cycle consists of two main phases: Interphase and M phase. Interphase is the preparatory phase where the cell prepares for division, while M phase is when actual cell division occurs.

2. **Divisions of Interphase**: Interphase is further divided into three sub-phases: G1 phase, S phase, and G2 phase. Each phase has specific functions.

3. **G1 Phase**: During the G1 phase, the cell grows in size and synthesizes proteins necessary for DNA replication.

4. **S Phase**: The S phase is crucial as it is the phase where DNA replication occurs. Importantly, this is also the phase where centriole duplication takes place. Centrioles are duplicated in the cytoplasm during this phase.

5. **G2 Phase**: In the G2 phase, the cell continues to grow and synthesizes proteins, preparing for mitosis or meiosis.

6. **Conclusion**: Based on the functions of each phase, it is clear that the duplication of centrioles in animal cells occurs during the S phase of interphase.

**Final Answer**: The duplication of centrioles in animal cells occurs during the S phase.

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