An object in which no light rays can pass through is called—

The correct option is opaque.

Objects are classified into three primary categories based on how much light can pass through them:

1. Opaque Objects: These are materials that do not allow any light to pass through them. When light falls on an opaque object, the light is either absorbed or reflected back. As a result, you cannot see through them at all, and they cast dark shadows. Examples include wood, metals, stone, and cardboard.
2. Transparent Objects: These materials allow almost all light to pass through them completely, allowing objects behind them to be seen clearly (e.g., clear glass, clean water, air).
3. Translucent Objects: These materials allow only some light to pass through them, causing objects behind them to appear blurry or partially visible (e.g., frosted glass, butter paper).

Since an object that allows no light rays to pass through it is defined as opaque, the correct choice is opaque.