When dividing cells are examined under a light microscope, chromosomes first become visible during-

Options

A. lnterphase
B. Prophase
C. Metaphase
D. `G_(2)` and S phases

Answer

To answer the question "When dividing cells are examined under a light microscope, chromosomes first become visible during," we can follow these steps:

### Step-by-Step Solution:

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

2. **Identifying the Phases of Mitosis**: The M phase is further divided into several stages: prophase, metaphase, anaphase, and telophase.

3. **Chromatin vs. Chromosomes**: During interphase (G1, S, G2), chromatin (the relaxed form of DNA) is present, and chromosomes are not yet visible under a light microscope.

4. **Prophase**: As the cell enters the M phase, specifically during prophase, the chromatin condenses to form distinct chromosomes. This is the first stage of mitosis where chromosomes become visible.

5. **Conclusion**: Therefore, the correct answer to the question is that chromosomes first become visible during prophase.

### Final Answer:
Chromosomes first become visible during prophase.

---