In what phase do chromosomes become visible during cell division?

During cell division, chromosomes become visible during prophase. This is the stage where chromatin, which is the relaxed form of DNA, condenses into distinct chromosomes that can be seen under a microscope. Each chromosome is made up of two sister chromatids joined at the centromere. The visibility of chromosomes is important for ensuring that they can be accurately separated during further phases of cell division.

By contrast, in interphase, chromatin is not condensed, making chromosomes invisible. During metaphase, chromosomes are aligned at the metaphase plate, but they are already visible as distinct entities. In telophase, chromosomes start to de-condense back into chromatin, again making them less visible. Therefore, the phase where chromosomes first become uniquely identifiable is indeed prophase.