Which of the following is NOT a type of firearm?

The correct answer identifies a type of operation rather than a physical type of firearm. When discussing firearms, the terms "lever," "pump," and "break" refer to specific mechanisms used to load and fire ammunition.

A lever-action firearm uses a lever to cycle the action and load the next round. Pump-action firearms require the user to manually pump the fore-end of the gun to eject the spent shell and chamber a new round. A break-action firearm operates by breaking open at the hinge to load and unload cartridges, often found in shotguns and some rifles.

In contrast, the term "automatic" refers to a classification of operation for firearms, specifically denoting the capability of the firearm to automatically cycle the action after firing a round. This is typically associated with automatic or semi-automatic firearms, which can include both pistols and rifles. Therefore, "automatic" does not fit as a type of firearm in the same way the others do, as it describes functionality rather than a specific mechanism or design.