At the end of Rarity's fashion show, Applejack faces a difficult choice she has to make, as her vote is going to decide the winner. She had put Rarity, judges and, most of all, the participants through a lot that day. Honesty or not, she can't afford to hurt any of them anymore. Having considered that, she discovers the other Element... the one that is as close to Honesty as can be.

Justice.

This story is just my depiction of the scene that has been left behind the curtain and is 100% canon-friendly!