Final answer:
Vestal Virgins prepared the mola salsa, a mixture of salted flour, used for sprinkling on sacrificial animals in ancient Roman rituals.
Step-by-step explanation:
The mola salsa that was sprinkled on the heads of the sacrificial animals during ancient Roman rituals was prepared by the Vestal Virgins. These were priestesses of Vesta, the goddess of the hearth, and part of their sacred duties included the preparation of the mola salsa, a mixture of salted flour, for use in public sacrifices. This ritual substance held significant religious importance and was integral to various ceremonial practices.