Final answer:
A single conductor must be insulated and have a metallic braided shield to be classified as a cable designed to carry RF energy, referred to as a coaxial cable.
Step-by-step explanation:
To be classified as a cable, particularly one that is designed to carry Radio Frequency (RF) energy, certain characteristics are required. A single conductor that qualifies as a cable should be insulated and have a metallic braided shield, to protect the inner conductor from the external electromagnetic interference. This describes a coaxial cable, which has a central conductor surrounded by insulation, itself encased within a cylindrical conducting shield, usually followed by an outer insulative layer.
Coaxial cables are crucial in applications that require the minimization of noise and interference, ensuring that the signal carried is not degraded substantially over distance. Hence, to be precise, a cable should both be insulated and have a metallic braided shield.