Final answer:
In the mid-1980s in New York, Graffiti art became an illegitimate form of art, often criticized as vandalism despite its role in social and political expression.
Step-by-step explanation:
The type of art that became illegitimate in the mid-1980s in New York was A. Graffiti art. Graffiti has been seen as a powerful platform for political expression and social commentary, particularly in urban areas. Despite its potential as a form of artistic resistance, graffiti art has often been met with opposition, being labeled as vandalism or visual pollution. Artists like Jean-Michel Basquiat, who began tagging as SAMO, brought attention to graffiti art with their works. The mid-1980s marked a period during which street art experienced both criminalization and burgeoning recognition.