"nightline" welcomes abc's adrienne bankart. >> college senior rachel mallenson soaking up every lasther senior year at university of texas austin. >> i'm so excited, i'm ready to graduate. >> reporter: earlier this week the 22-year-old was crowned miss black ut. >> when they announced my name, the first thing i honestly thought was, wow. >> reporter: but her celebration has been sidelined by controversy. >> one moment i'm on cloud nine. people agreed that i was worthy enough to win the title. the next minute, i'm not black enough, and i don't deserve this. >> reporter: just hours after receiving the crown a vocal group of people took to twitter saying rachel, who is biracial, should not have won. because she isn't black enough. >> one tweet says, she's clearly the lightest damn near white-looking black woman, and she quit playing dumb, guys, it looks sketchy. >> reporter: one writing, of course they choose the most white-skinned, least black-looking person there. another saying, they should have pulled out the brown paper bag test. the pageant, in its 35th year, hosted by the histori