Final answer:
Double action in a handgun refers to the trigger performing both the cocking of the hammer and the release to fire the gun with a single pull.
Step-by-step explanation:
With regards to a handgun, "double action" means the trigger performs two actions: cocking the hammer and releasing it to fire the gun. This term does not refer to the gun firing two bullets with a single pull of the trigger, having two barrels, or having a double magazine capacity. Instead, double action is a feature that simplifies the process of firing the weapon as it negates the need for a separate cocking action before firing.