If a white Aura is attached to a creature with protection from white, what happens to the Aura?

When a white Aura is attached to a creature that has protection from white, the Aura is put into its owner's graveyard. This is because protection from a color grants several benefits, one of which is that the affected permanent cannot be enchanted, equipped, or blocked by anything of that color.

In this context, a white Aura is considered an effect or attribute that directly influences the creature it is attached to. Since the creature with protection from white cannot be enchanted by the Aura, the rules dictate that the Aura must be put into the graveyard. This outcome is a crucial aspect of understanding how protection functions in the game: when a permanent cannot interact due to its protection, any effects that attempt to do so must be removed in accordance with the rules.

The other options incorrectly interpret how protection interacts with Auras. The Aura cannot stay attached without effect, nor can it be returned to hand or remain attached to another creature, as those would not align with the rules regarding protection and enchantments.