In which of the following phases does the formation of spindle fibers around the centrosome occur?

Match the following:

Column-$I$	Column-$II$
$1$. Metaphase	$p$. Chromosomal material condensed
$2$. Prophase	$q$. Nucleolus reform
$3$. Anaphase	$r$. Spindle fibre attach to kinetochores
$4$. Telophase	$s$. Chromatids move to opposite poles

$A$ student observed a slide of mitosis under the microscope and noted that the chromosomes were positioned at the opposite poles. Which stage was the student observing?

During anaphase,the chromatids move towards the poles due to which of the following?

What stage occurs before the cell enters mitosis?

Spindle fibers are primarily composed of which protein?