Final answer:
Kinetochore microtubules are the spindle fibers that extend from the poles of a cell to the kinetochores on chromosomes, playing a key role in chromosome segregation during cell division. Option a.
Step-by-step explanation:
The spindle fibers that extend from pole to kinetochore are known as kinetochore microtubules. These fibers are fundamentally crucial during the process of cell division, particularly in the phases of mitosis such as prometaphase and metaphase.
The kinetochore microtubules attach to a special protein structure on the chromosome called the kinetochore. This attachment is essential for properly segregating the chromosomes into the two daughter cells.
Other spindle fibers include polar microtubules, which assist in elongating the cell, and astral microtubules, which help orient the spindle apparatus.
So Option a is correct.