I had to go with Alternative because it's Punk and Ska for me. Although I don't like using the term "alternative" because it's such a broad term that encompasses too many different types of music to really define anything. Punk and Ska are too very linked genre's of music, but they're very very different to Metal and indie and don't deserve to be lumped in together. Then Punk is one of the most diverse genres of music there is, you've got Anarcho-punk, Celtic punk, Street punk, Hardcore punk, Skate punk, Punk Rock, Ska punk, then you can go into how it's a way of thinking and a set of ideal's before it's music, rather than a way of life attached to the music, the music is attached to the way of life so the music can be almost anything so long as it matches the ideals.
Basically Punk's one the most complex, diverse, intelligent and powerful genre's music there is, it's a lot more than a bunch of thugs yelling anarchy as many people think, there are some damn smart punk rockers, Greg Graffin, the front man for Bad Religion (going for over 30 years) has a PHD in zoology and lectures life sciences at UCLA.