When does a runner return to base after an umpire's interference?

In the context of an umpire's interference in baseball, the appropriate situation in which a runner returns to base is indeed when the runner is not put out as a result of the play. Umpire interference typically requires that the players be put in the same position as if the interference had not occurred. If the runner is not tagged out during the play, they are permitted to return to their original base. This ensures that the interference does not penalize the runner if they have not been directly affected by the events following the interference.

The emphasis is on the outcome of the play in relation to the interference. When a runner successfully avoids being put out, they retain their right to return, highlighting the intention of the rules to protect players from adverse situations that arise due to calls or actions that are outside the normal flow of the game.

The other options present scenarios that either misinterpret the timing of the play's resolution or do not take into account the conditions surrounding the interference accurately.