A cable consisting of a central metallic inner conductor separated from an enclosing outer conductor by a dielectric material is called ____________.

The description given in the question highlights the structure of a coaxial cable, which consists of a central metallic inner conductor that transmits signals, surrounded by a dielectric insulator, and then an outer metallic conductor that serves as a shield against electromagnetic interference and completes the circuit. This configuration not only protects the integrity of the signals being transmitted but also allows for effective propagation of high-frequency signals over longer distances.

Twisted pair cables, in contrast, consist of pairs of insulated copper wires twisted together to reduce electromagnetic interference, rather than the concentric layers found in coaxial cables. Fiber optic cables utilize light to transmit data and consist of a core, cladding, and protective outer layers, completely different from the metallic components of coaxial cables. Shielded cables, while they may contain conductors shielded from interference, do not specifically describe the central conductor and dielectric structure characteristic of coaxial cables.

Thus, the answer emphasizes the unique structural elements of coaxial cable, making it the correct response to the question presented.