The craftsmen in the play speak in prose because

ATheseus would have forbidden them to use verse.
Btoo much blank verse gets tiresome.
Cthat kind of common language symbolizes their status in life.
Dit's the language of love.

Verified Answer :

Kbest
Cthat kind of common language symbolizes their status in life. 

The craftsmen in the play speak in prose because: that kind of common language symbolizes their status in life. Option C is correct.

I think that any craftsman would speak very posh and in a high register  language of poetry, hence they speak in prose, which is not that classy.

Prose is a form of language that conveys a natural flow of speech and grammatical structure instead of a regular rhythmic structure as in traditional poetry.