What is tissue culture useful for?

Statement $P$: Callus culture medium contains auxin and cytokinin.
Statement $Q$: They are growth promoters and initiate cell division.

Which statement is most appropriate for plant tissue culture?

To obtain callus from the internodal segments of tobacco stems,what is added to the medium in addition to auxin?

Arrange the following steps of somatic hybridisation in a correct sequence.
$A$. Digestion of cell walls.
$B$. Isolation of naked protoplasts.
$C$. Fusion of protoplasts to get hybrid protoplast.
$D$. Isolation of single cells from two different varieties of plants.
$E$. Growing of hybrid protoplast to form a new plant.
Choose the correct answer from the options given below:

Somaclonal variation appears in plants: