Why is the incubation carried out in the dark?any specific...

To see what exactly the staining solution is see under "Recipes" item 2. The correspondent will see there is not exactly a staining solution A nor staining solution B. There are three stock solutions to prepare, before proceeding to make the staining solution.

May I know what exactly is the staining solution A and staining solution B that is used for preparation of SA-ß-gal solution?

Thank you for the answer..

It was in dark because X-gal the substrate is light sensitive.