B-2

B-2 can refer to the following:
 * World B-2 from Super Mario Bros.: The Lost Levels.
 * Room B-2 from Mario vs. Donkey Kong: Minis March Again!.
 * The Pinwheel Gate, mission B-2 from Luigi's Mansion: Dark Moon.
 * Level B-2 from Mario vs. Donkey Kong: Tipping Stars.

B-2