Which of the following phases is non-divisional?

The cell cycle is divided into two basic phases. What are those phases?

Select the correct statements regarding $S$-phase of interphase:
$I.$ Occurs between $G_{1}$ and $G_{2}$ phases.
$II.$ $DNA$ replication begins in the nucleus.
$III.$ Centrioles duplicate in the cytoplasm.
$IV.$ As $DNA$ is doubled,the number of chromosomes also doubles.
The option with correct statements is:

In the given diagram of the cell cycle,in which phase is the $DNA$ polymerase enzyme required?

Which phase is the initial phase of interphase?

If a cell is diploid $(2n)$ in the $G_1$ phase,then in the subsequent $S$ phase,the cell will remain/become ........