Answer:
A. Anaphase
Step-by-step explanation:
Cohesin is a protein that holds sisters chromatids together. Anaphase begins with the cleavage of that protein, enabling centromeres to split, and the movement of sister chromatides (new daughter chromosomes) toward the poles.
During the anaphase, microtubules that are not attached to chromosomes elongate and push apart. This elongation makes the cell longer and separates the poles.