Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous: Air, water, a piece of rock, a sheet of aluminium, a mirror, a wooden board, a CD, smoke, a sheet of plain glass, fog, a piece of red-hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the flame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, Sun, firefly, moon.

Use the idea that opaque is not transparent in this case, while translucent is semi-transparent, and later in the solution, use the fact that non-luminous elements don't have their own light; instead, they receive light from other sources and shine later, for example the moon, to illustrate how non-luminous elements don't have their own light.
Opaque means that you can't see through it, thus it's not transparent.
Transparent: Visible through.
The ability to transmit light through a substance without significant light dispersion is known as transparency. Different materials with varying refractive indices make up translucent material.
Contrarily, transparent materials are made up of refractive index-uniform constituents.
Luminous: Has to do with how light appears to the eye rather than how much energy it contains.

The opposite of bright is non-luminous.

The classification of the following things is provided below based on the aforementioned definitions:

Hence, the correct answer is option D.