How to...

Can someone please explain now to eliminate B?

Hi, I don't think there's anything about fairness in what is described. In fact, both policies are equally fair. In both cases those using a card are charged the same amount more than people using cash. The difference is that in one case the difference is framed as a gain for cash users, and in others it's framed as a penalty for card users. In neither case were people more or less advantaged by the actual policy since the policies had the same effect.