In is very difficult to stop cell division when the cell has entered

Options

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

Answer

To solve the question "In is very difficult to stop cell division when the cell has entered...", we need to analyze the phases of the cell cycle and identify which phase makes it challenging to halt cell division.

### Step-by-Step Solution:

1. **Understanding the Cell Cycle**: The cell cycle consists of several phases, primarily divided into Interphase and Mitotic Phase. Interphase includes G1, S, and G2 phases, while the Mitotic Phase includes M phase (mitosis).

2. **Identifying the Phases**:
- **G1 Phase**: The cell grows and prepares for DNA replication. Cells can enter a resting state (G0) from here.
- **S Phase**: This is the synthesis phase where DNA replication occurs. The cell's DNA content doubles during this phase.
- **G2 Phase**: The cell continues to grow and prepares for mitosis.

3. **Key Characteristics of the S Phase**:
- During the S phase, the DNA is replicated, resulting in a doubling of the genetic material.
- Once a cell has entered the S phase, it is committed to completing the cell cycle because it cannot revert to a previous phase without completing DNA replication.

4. **Conclusion**: Since the question asks when it is difficult to stop cell division, the answer is during the **S phase**. Once the cell has started replicating its DNA, it must continue through the cycle to complete the division process.

5. **Final Answer**: The correct option is **S Phase**.