What are examples of solid conductors?

Solid conductors are materials that can efficiently transport electric current through them in a solid state. Metals are excellent examples of solid conductors because they have free-moving electrons that allow for easy flow of electricity. This property makes metals such as copper, aluminum, and silver widely used in electrical wiring and components.

In contrast, gases and plastics serve as insulators rather than conductors, as they do not have free electrons that facilitate the flow of electricity. Liquids may conduct electricity, but in the context of this question, they are not considered solid conductors since they are not in a solid state. Therefore, metals stand out as the correct answer due to their inherent conductive properties and structure.