What type of action does a shotgun NOT have?

A shotgun does not have a double action mechanism. The term "double action" typically refers to a firearm mechanism where pulling the trigger performs both the cocking and firing actions, which is commonly found in handguns.

In contrast, shotguns generally employ several other mechanisms for operation. For example, pump action shotguns require the user to manually slide the fore-end back and forth to eject spent shells and chamber a new round. Break action shotguns operate by having the barrel(s) hinge down to allow for easy loading and unloading, while bolt action, though predominantly associated with rifles, is a mechanism where the shooter manually operates a bolt to chamber rounds.

Therefore, the absence of a double action mechanism in the typical configurations of shotguns makes it the correct answer to this question.