When school friends use slang, it is considered casual. Option B is correct.
Slang refers to a language (words, phrases, and usages) of an informal register that members of particular in-groups favor (over the common vocabulary of a standard language) in an attempt to establish group identity, exclude outsiders, or both.
The word slang referred to the vocabulary of "low" or "disreputable" people.
Some believe that slang exists due to the fact that we must come up with ways to define new experiences that have surfaced with time and modernity.
