What ruling states that runners must retouch their bases after a caught foul fly?

When a foul ball is caught in baseball or softball, the ruling is that runners must retouch their bases. This requirement serves to ensure that the base runners fulfill their obligation to properly navigate the bases after the ball has been caught, reflecting the fundamental rules of base running.

When the ball is caught, it is considered a dead ball situation for the runners, meaning they must return to their previous base before they are allowed to advance again on a subsequent play. This rule emphasizes the importance of proper base running mechanics and ensures fairness by requiring the runners to only advance after properly retouching bases.

The other options do not align with the rules, as they suggest that runners can either advance unrestricted or ignore the need to retouch, which contradicts the basic principles of base running in this scenario. The incorrect options undermine the integrity of the game and the responsibilities that runners have during play.