Range testing: Has nothing to with where the deer and the antelope play, nor does it involve a pencil or scantron sheet. They just want to see “how many notes ya got.”
Singing an a cappella piece of your choosing: a cappella is not the title of a song, but just a fancy way of saying “they ain’t nobody goin’ be play with ya.” It is from the Italian, meaning “in the manner of the church.” (Extra credit for those that Googlelessly guess what the opposite of a cappella is.)
While you do not need to sing a religious song, as a cappella might suggest, you may want to avoid “Ein Ton” by Peter Cornelius for this particular audition. (“Ein Ton” translates to “One Tone,” which would not bode well for your range testing, unless you plan to bring the deer and the antelope.)
I hope that you find these tips and tidbits helpful or at the very least befuddling.