What characteristic does a material have if it is impossible to see through and prevents the passage of light?

A material that is impossible to see through and prevents the passage of light is characterized as opaque. Opaque materials do not allow light to pass through them, meaning that when light hits their surface, it is either absorbed or reflected rather than transmitted. This means that objects behind an opaque material cannot be seen, as no light from those objects can reach the observer's eyes.

In contrast, translucent materials allow some light to pass through but scatter it, making objects behind them appear blurred. Transparent materials, on the other hand, allow light to pass through with minimal scattering, allowing for clear visibility of objects behind them. Reflective materials, while they may prevent light from passing through in the sense that they bounce light back, do not fit the definition of being unable to allow any passage of light like opaque materials do. Therefore, the defining feature of an opaque material is its complete blockage of light, making it the correct answer.