Which group of priests in Rome was known for their dance during religious ceremonies?

The Salii were a group of priests in ancient Rome, specifically known for their role in the worship of the war god Mars. They were distinguished by their performance of ritual dances during various religious ceremonies, particularly the festival of the Salii known as the "Salia." This celebration involved the priests dancing and singing as they carried the sacred shields (ancilia) that were believed to have been given to the Romans by the god.

The other groups mentioned had different responsibilities: the Augures were primarily concerned with interpreting the will of the gods through the study of auspices, the Flamines were priests assigned to specific deities who conducted more formal rituals, and the Quindecemviri were responsible for the maintenance of the Sibylline Books and also conducted important rites, but they did not have a specific role related to dance. Thus, the unique association of the Salii with dance during religious occasions clearly identifies them as the correct answer.