Which part of cells disintegrate at the end of prophase?

At metaphase,chromosomes are attached to the spindle fibres by their

$S$ - Statement: During anaphase,the paired chromatids separate.
$R$ - Reason: During anaphase,the spindle fibers shorten,and the centromere splits.

Choose the correct combination of options to select the correct statement for prophase:
$I.$ Chromosomal material condenses to form compact mitotic chromosomes.
$II.$ The assembly of mitotic spindle is initiated by the microtubules.
$III.$ Cells do not show organelles when viewed under the prophase.
$IV.$ The nucleolus or nucleoli degenerate completely.

The chromosomes align at the equator during

In which of the following stages is the number,size,and shape of chromosomes most clearly visible?