The characteristic of this stage of mitosis is the separation of the sister chromatids

The correct option is Anaphase.

Mitosis is the process of cell division that results in two genetically identical daughter cells. It is divided into several distinct stages: prophase, prometaphase, metaphase, anaphase, and telophase. Each stage is characterized by specific cellular activities and structural rearrangements of the chromosomes.

During Anaphase, the sister chromatids, which were previously aligned along the metaphase plate in the center of the cell, are separated. The protein "glue" (cohesin) that holds the sister chromatids together is cleaved, allowing them to become individual chromosomes. The spindle fibers (microtubules) then shorten, pulling the newly separated chromosomes toward opposite poles of the dividing cell.
This ensures that each of the future daughter cells receives an identical and complete set of chromosomes.