What role do microtubules play during anaphase?

Microtubules play a crucial role during anaphase by depolymerizing to facilitate the movement of sister chromatids toward opposite poles of the cell. As the sister chromatids are separated, the microtubules that are connected to them, specifically the kinetochore microtubules, shorten by breaking down their tubulin subunits. This action effectively pulls the chromatids apart, ensuring that each new daughter cell will receive an identical set of chromosomes.

The other options relate to different phases or processes in cell division. Chromatin condensation occurs during prophase, the formation of the cleavage furrow is associated with cytokinesis (which follows mitosis), and the nuclear envelope reforming occurs during telophase. These processes are distinct from what happens during anaphase. Thus, the statement about microtubules depolymerizing to separate sister chromatids accurately describes their role specifically during this stage of cell division.