Answer:
polar microtubules contract, pulling attached chromosomes toward the poles.
Explanation:
Polar microtubules are one of the two types of microtubules that together make the mitotic spindle. The polar microtubules are the ones that extend from each pole to the cell's equator.
At the equatorial region, the polar microtubules from two poles overlap. Also known as non-kinetochore microtubules, the polar microtubules do not get attached to the kinetochores of chromosomes.
The function of the polar microtubules is to assist in chromosome separation during anaphase. The polar microtubules from two poles slide past each other. As they slide, the degree of overlap is reduced and the two opposite poles are pushed apart.
The reduced overlap between the polar microtubules indirectly moves the chromosomes apart as the kinetochore microtubules attach the chromosomes to the opposite poles.