Which characteristic indicates a possible mine-like object based on its movement?

A change in aspect indicates a possible mine-like object based on its movement because it refers to the orientation or appearance of the object as it shifts in relation to an observer or sensor. When an object exhibits a significant alteration in how it presents itself—such as rotating, tilting, or varying in shape—it could suggest that the object is mobile and may behave similarly to a mine, which is often designed to be discreet and evade detection. For example, as a mine shifts position due to environmental factors or active mechanisms, it may change how it appears and interacts with light or sensors.

The other characteristics mentioned—size, shadow, and ringing—do not directly relate to the movement of an object in the same manner. Size may provide information about the dimensions of an object, but it does not indicate movement. A shadow can give clues about the object's position or shape but does not inherently indicate its movement. Ringing could refer to acoustic signals, which might suggest the presence of an object but not specifically its mobility. Therefore, aspect change is the most relevant characteristic for identifying the potential movement of a mine-like object.