During which festival is the sacrifice of a pig, sheep, and bull to Mars performed?

The festival during which the sacrifice of a pig, sheep, and bull to Mars is performed is known as the Suovetaurilia. This ancient Roman rite was integral to agricultural and military contexts. It involved the ceremonial sacrifice of these animals, which were representative of different aspects of Roman society and utility. The ritual was primarily intended to purify the fields and ensure good harvests, and it was often performed to ask for the favor and protection of Mars, the god of war, who also had associations with agricultural fertility.

The other festivals listed do not involve this specific ritual. Vinalia Rustica celebrates the wine harvest and the fertility of the grapevine, focusing on offerings related to wine rather than livestock. Robigalia is dedicated to Robigus, a deity associated with the protection of crops, and focuses on different rites. Parilia is a pastoral festival associated with shepherding and the protection of livestock, but it does not specifically involve the sacrifice of these particular animals to Mars. Thus, the Suovetaurilia is unique for its specific animal sacrifices and its connection to Mars, making it the correct answer.