What occurs during the anaphase of mitosis?

During anaphase of mitosis, the defining event is the separation of sister chromatids, which are the duplicate copies of each chromosome. This stage is characterized by the movement of these sister chromatids toward opposite poles of the cell. The centromere, which holds the sister chromatids together, splits, and the spindle fibers pull the now-separated chromatids apart, ensuring that each new daughter cell will receive an identical set of chromosomes. This movement is crucial for maintaining genetic consistency during cell division, resulting in two daughter cells with the same number of chromosomes as the original cell.

The other choices describe different stages or processes. For example, the alignment of chromosomes in the middle of the cell happens during metaphase, while the reforming of the nuclear envelope occurs in telophase. Additionally, DNA condensation takes place in prophase when chromatin coils into visible chromosomes, laying the groundwork for the subsequent separation of genetic material.