What characteristic distinguishes a dud?

The characteristic that distinguishes a dud is that it has failed to explode. A dud refers to an explosive device that was intended to detonate but did not do so for some reason. This might be due to a malfunction in the device, insufficient initiation energy, or issues with its components. Understanding this definition is crucial because recognizing a dud impacts how EOD specialists handle such devices, as they can pose a potential risk during operations, despite not having detonated.

The other choices might initially seem plausible in different contexts but do not capture the essence of what defines a dud. For example, a device designed for safe detonation does not represent a dud, as it is meant to function in a controlled manner. Similarly, devices used for training purposes are often inert or intentionally made safe, again differentiating them from duds. Lastly, an active and functional device signifies that it is capable of detonation, which is the opposite of a dud's defining feature.