Which characteristic is true of a single-action revolver?

A single-action revolver is designed with a specific mechanism that distinguishes it from other types of firearms. The characteristic that is true of a single-action revolver is that cartridges must be loaded and unloaded through the loading gate. This design allows the shooter to load individual cartridges into the chambers of the cylinder via a small opening known as the loading gate, which is located on the side of the revolver.

In a single-action revolver, the user must manually pull back the hammer to prepare the gun to fire, and this action typically occurs after rotating the cylinder to align a cartridge with the barrel. Each time the trigger is pulled, it only releases the hammer, hence the term "single-action."

This mechanism emphasizes the importance of the loading gate for both loading and unloading cartridges. It is a classic design seen in many historical revolvers, providing a straightforward and reliable method for handling ammunition.

Other options do not accurately describe the single-action revolver's functionality. For example, while a single-action revolver can indeed hold multiple rounds within its cylinder, the focus here is on the method of loading and unloading, which is specifically through the loading gate.