Here's why:

* Microtubules are long, hollow tubes made of the protein tubulin. They are part of the cytoskeleton, providing structure and support to the cell.

* During mitosis and meiosis, microtubules assemble into structures called spindle fibers. These fibers attach to the chromosomes at specialized regions called kinetochores.

* Motor proteins associated with the microtubules use ATP (energy) to pull the chromosomes towards opposite poles of the cell, ensuring that each daughter cell receives a complete set of chromosomes.

Key takeaway: Microtubules, through spindle fibers, are the essential players in chromosome movement during cell division.