From which of the following do spindle fibers originate?

How do the chromosomes appear in the given figure?

In which stage of cell division do the chromosomes align at the equator?

Select the correct statement regarding $S-$phase of interphase.
$I.$ Occurs between $G_1$ and $G_2$ phase.
$II.$ $DNA$ replication begins in the nucleus.
$III.$ Centrioles duplicate in the cytoplasm.
$IV.$ As $DNA$ is doubled,the number of chromosomes also doubles.

Spindle fibres attach on to

The cause of chromosomal movement during anaphase is ........