If F4 fields a ball and throws it into the stands while R2 and R1 are on second and first base, what is the ruling?

When F4 fields a ball and throws it into the stands, this action is interpreted as a deliberate act that allows runners to advance due to an error by the defense. In this situation, since the throw to the stands is considered an illegal throw resulting in the ball being out of play, all runners on base—R2 who is on second base and R1 who is on first—are entitled to two bases from their respective positions at the time the ball left the field.

This ruling follows the guideline that if a fielder throws the ball out of play, all runners are permitted to advance two bases. R2, who was at second base, would thus be awarded home plate, while R1, who was at first base, would advance to third base. Therefore, the understanding of the specific rule regarding an overthrow or an error that sends the ball out of play supports why the correct answer indicates that all runners are awarded two bases.