Final answer:
The Jaz Zagals were singing "It's Raining Men" when Moira auditioned. This iconic song was made famous by The Weather Girls and is often sung by choirs.
Step-by-step explanation:
The song the Jaz Zagals are singing when Moira shows up to audition in the television series is called "It's Raining Men." This song was originally performed by The Weather Girls in the 1980s and has since become a classic hit, often associated with female vocal groups and choirs. Moira’s audition with the Jaz Zagals showcases her vocal talent and is a memorable moment in the series.