While the opinion that "many people do not care for this style of art so they protest it" (option 1) can be a part of the discussion around graffiti, it is not as central to the issue as option 2.
The main reason graffiti is often viewed negatively in society is due to the fact that it often involves vandalism—specifically, the act of defacing property without permission (option 2). This view is rooted in concerns about respect for public and private spaces, property rights, and community standards.
While some people may dislike graffiti as a form of art and express their dissent, the legal and societal implications of graffiti are primarily tied to property damage and vandalism, making option 2 the stronger choice.
If you have more thoughts on this or want to discuss it further, I'd love to hear them!