How does an electric discharge produce light?

An electric discharge produces light primarily by passing a current through a gas or vapor. When an electric current flows through a gas, it provides energy to the atoms or molecules in that gas. This energy excites the electrons to higher energy levels. When the excited electrons return to their original energy states, they release energy in the form of light. This process is what creates the visible spectrum that we see, such as in neon lights or lightning.

The other options involve different mechanisms for producing light. Heating a solid material generally refers to incandescence, which creates light through heat rather than electrical discharge. Reflecting sunlight involves no energy transition in the material itself but instead relies on the surface properties of an object. Chemical reactions can produce light, but that process is distinct from the electrical excitation of gas. Hence, passing a current through a gas or vapor is the process that accurately describes how electric discharge generates light.