What should I sing for an a cappella audition?!?

I am a little unsure about what I should sing for an audition for an a cappella group that sings modern music. My range is from C3 to G5 and I'm generally placed as an alto because of my low range. I have sung things by Sara Bareilles, Carol King, and Judy Garland so I guess you could base suggestions off of that. I'm looking for an a cappella solo, and I'm up for anything!!!