During telophase in mitosis, the cell is nearing the completion of division. This stage is characterized by several critical changes. One of the hallmark events is the disassembly of spindle fibers that were crucial for separating the chromosomes during the earlier phases of mitosis. As the tension created by the spindle fibers is removed, the individual chromatids that were pulled apart begin to relax and de-condense back into a less compact form known as chromatin. This unwinding is essential because it allows the genetic material to revert to a state that enables transcription and replication in the future.
In contrast, the other phases described in the options refer to earlier steps in mitosis. For instance, chromosomes lining up at the center corresponds to metaphase, while the separation of chromosomes to opposite ends signifies anaphase. The visibility of chromosomes and their attachment to spindle fibers refers to prophase. Thus, the correct identification of the processes occurring during telophase emphasizes the transition from the actively dividing state back to a more typical interphase condition for the cell.