During cell growth, DNA synthesis occurs in:

Options

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

Answer

To answer the question "During cell growth, DNA synthesis occurs in:", we need to analyze the different phases of the cell cycle.

### Step-by-Step Solution:

1. **Understanding the Cell Cycle Phases**:
- The cell cycle consists of several phases: G1 (Gap 1), S (Synthesis), G2 (Gap 2), and M (Mitosis).

2. **Identifying the M Phase**:
- The M phase is where mitosis occurs, and the cell divides into two daughter cells. DNA synthesis does not occur in this phase.

3. **Identifying the S Phase**:
- The S phase is specifically known as the synthesis phase. This is the phase where DNA replication occurs, meaning that the DNA is synthesized and duplicated.

4. **Identifying the G1 Phase**:
- The G1 phase is known as the first growth phase. During this phase, the cell grows in size and synthesizes RNA and proteins, but not DNA.

5. **Identifying the G2 Phase**:
- The G2 phase is the second growth phase, where the cell prepares for mitosis. Some proteins are synthesized, but again, DNA synthesis does not occur in this phase.

6. **Conclusion**:
- Based on the analysis, the correct answer to the question is that DNA synthesis occurs during the S phase of the cell cycle.

### Final Answer:
DNA synthesis occurs in the S phase.

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