What is a conductor?

A conductor is fundamentally defined as a material that allows electricity to flow freely. This characteristic is critical in the field of electricity and electronics, as it enables the transmission of electrical energy through various circuits and applications. Conductors typically have a high density of free electrons, which are essential for the flow of electrical current. Common examples of conductors include metals like copper and aluminum, which are widely used in wiring and electrical components due to their excellent conductivity.

The other options, while related to electrical concepts, describe different components or tools that do not fit the definition of a conductor. A device that stores electrical energy refers to capacitors or batteries, tools used to measure electrical resistance pertain to instruments like ohmmeters, and safety devices for circuit protection include fuses and circuit breakers. None of these alternatives possess the fundamental property of facilitating the flow of electricity like a conductor does.