Which of the following materials can be classified as a conductor?

Copper is classified as a conductor because it has high electrical conductivity, allowing electrical current to pass through it easily. This property arises from its atomic structure, which has free electrons that can move readily under the influence of an electric field. This makes copper an ideal choice for electrical wiring and various applications in electronics and electrical systems.

In contrast, rubber, wood, and glass are considered insulators. Insulators have tightly bound electrons that do not move freely, which prevents electric current from passing through. This makes them suitable for protecting against electrical currents and is why materials like rubber are often used to coat wires for safety.