In mitosis,the spindle fibers are ........

The period of active mitosis typically ranges from:

At the end of which phase is the number of chromosomes at each pole equal to the number of chromosomes in the parent cell?

In which phase are chromosomes most easily observed?

$A$: The complete disintegration of the nuclear envelope marks the start of metaphase.
$R$: Chromosomes are distinct with two chromatids at this stage.

Which stage is represented by the given figure?