When Twilight considers giving up her own ticket so two of the others can go, she says that'll still leave three of her friends unhappy and imagines a crying Rainbow Dash, Rarity and Pinkie Pie, implying that Applejack and Fluttershy were the ones she was considering giving the tickets to. It makes a lot of sense when you consider Applejack has the most selfless reason for wanting to go (and has first dibs) and Fluttershy was the most polite about asking.
