I selected the Carbine.
My definition of a "carbine" is a repeating rifle with a 16-18" barrel that fires a light to medium caliber cartridge. Something light and quick handling. e.g. M1 Carbine, bullpup semiauto, a short lever action carbine, etc.
The carbine usually has sufficient power to handle CQB chores. Its light weight makes it easier to hold and the shorter size means it's easier to wield in smaller spaces.
The carbine, even in a pistol caliber, will increase velocity and hitting power. With a rifle cartridge, the power is greatly increased.
A shotgun offers a good compromise between power and hitting ability. The larger zone of contact favors the shotgun user, but if too many pellets miss it's not as effective.