Decision of `G_(0)`-phase occurs

Options

A. Towards the end of `G_(1)`-phase
B. Before middle of `G_(1)`-phase
C. At the end of telophase
D. Towards end of cytokinesis

Answer

### Step-by-Step Solution

1. **Understanding the G0 Phase**: The G0 phase, also known as the resting phase, is a state in the cell cycle where the cell is not actively preparing to divide. It can be viewed as an extended G1 phase where the cell is quiescent.

2. **Identifying the Checkpoints**: The cell cycle has several checkpoints that help the cell decide whether to proceed with division. The most important checkpoints are:
- G1 checkpoint
- G2 checkpoint
- Spindle checkpoint

3. **Focus on the G1 Checkpoint**: The G1 checkpoint is the primary decision point for the cell. It occurs during the G1 phase and is crucial for determining whether the cell will proceed to the S phase (where DNA is replicated) or enter the G0 phase.

4. **Timing of the G1 Checkpoint**: The G1 checkpoint occurs in the middle of the G1 phase. If the cell passes this checkpoint, it commits to division and moves into the S phase. If it does not pass, it may enter the G0 phase.

5. **Evaluating the Options**:
- **Option 1**: Towards the end of the G1 phase - Incorrect, as the decision occurs in the middle of the G1 phase.
- **Option 2**: Towards the middle of the G1 phase - Correct, as this is when the G1 checkpoint occurs.
- **Option 3**: At the end of the telophase - Incorrect, as telophase is part of mitosis, not the interphase.
- **Option 4**: Towards the end of cytokinesis - Incorrect, as cytokinesis is the final stage of cell division and does not involve a checkpoint.

6. **Conclusion**: The correct answer is that the decision for the G0 phase occurs towards the middle of the G1 phase.