Learn 5, Irish Song Tradition, Irish Dance Music and Sean nos are good ones to study since they come up in the Listening. Harping tradition and fusions are pretty easy as well. Remember, don't stress yourself about it, only write in bullet points if it's easier. You only have 15 minutes and it's not worth much, it is easy points however.
Irish Song Tradition,
Irish Dance Music,
Seán O' Riada and
The Irish Harp/ Harping Tradition are 5 that (usually) one will always come up. However, Paddy Moloney died around the time the papers were wrote, so lots of teachers are predicting The Uilleann Pipes to show up too