Audtion pieces for university -music?

They are telling you specifically what they want. What piece is good for someone else may not be a fit for you. They are leaving it open-ended to give you a choice in what you perform. The main idea is to see your perform in an array of different pieces, some slow, some fast, some more technical than others. When you think about which pieces you want to select try to keep in mind that they are also looking for potential in your personality, your technique and other things. Often they will not ask you to perform the entire piece, sometimes they will. I know that I began one piece and finished it and during the second piece they stopped me and wanted the next.