In the presence of a chromogenic substrate,what color colonies do recombinants and non-recombinants produce,respectively?

In which of the following methods is a probe allowed to hybridize to its complementary $DNA$ in a clone of cells?

The steps involved in the Southern blot test are as follows:
$I.$ $X-ray$ film
$II.$ Electrophoresis
$III.$ Digestion with restriction enzyme
$IV.$ Ethidium bromide
$V.$ Radioactive probe
Choose the option having the correct sequential order of these events.

After $4$ $PCR$ cycles,how many $DNA$ molecules are formed from one $DNA$ template molecule?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A$: In recombinant $DNA$ technology, lysozyme is used for disrupting bacterial cells while cellulase is for plant cells.
Reason $R$: Isolation of genetic material needs disruption of cells.
In the light of the above statements, choose the most appropriate answer from the options given below:

When a foreign $DNA$ is introduced into an organism,how is it maintained in the host and how is it transferred to the progeny of the organism?