Which of the following duplicates in cytoplasm in S-phase ?

Options

A. Chromosomes
B. Centrioles
C. Chromatid
D. DNA

Answer

To solve the question "Which of the following duplicates in cytoplasm in S-phase?" we need to analyze the options provided and understand the processes that occur during the S-phase of the cell cycle.

### Step-by-Step Solution:

1. **Understand the Cell Cycle**: The cell cycle consists of several phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis). The S-phase is specifically the phase where DNA synthesis occurs.

2. **Identify Key Events in S-phase**: During the S-phase, the primary event is the replication of DNA. This occurs in the nucleus, where chromosomes are duplicated to form sister chromatids.

3. **Examine the Options**:
- **Chromosome**: While chromosomes do get duplicated during the S-phase, this duplication occurs in the nucleus, not the cytoplasm.
- **Centrioles**: Centrioles are structures involved in cell division that duplicate during the S-phase. This duplication occurs in the cytoplasm.
- **Chromatid**: Chromatids are the result of chromosome duplication. They are not duplicated in the cytoplasm; rather, they are formed from the chromosomes during the S-phase in the nucleus.

4. **Conclusion**: Based on the analysis, the only structure that duplicates in the cytoplasm during the S-phase is the centrioles.

5. **Final Answer**: The correct answer is **Centrioles**.