Why did oscar wilde most likely use stock characters such as dandies in his works?
to contribute to the development of stock characters
to attack the fake morality and superficiality of victorian society
to demonstrate that he was a unique playwright
to earn a place for himself in high society

It is know that, although he was a writer/playwright/poet who worked in the Victorian era, Oscar Wilde was completely against it. He hated having to be such a hypocrite as the rest of the then society was, and fought to astonish the people, usually in a negative way. People either hated him or loved him. The correct answer here is the second one, "to attack the fake morality and superficiality of Victorian society". This is most evident in one of his best plays, "The Importance of Being Earnest". 

Ibeileve it will be c. : )