During which phase does $DNA$ replication occur?

In which of the following stages are the chromosomes least condensed?

Identify the correct statement with regard to $G_{1}$ phase $(Gap\,1)$ of interphase.

In the given figure,which phase is represented by '$a$'?

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:

During which phase is the cell metabolically active and continuously grows but does not replicate its $DNA$?