What defines an insulator?

An insulator is defined as a material that does not conduct heat or electricity well. This lack of conductivity is due to the structure and properties of insulators, which often have tightly bound electrons that do not move freely. As a result, insulators can effectively block the transfer of energy in the form of heat or electricity. This characteristic makes insulators useful in various applications, such as protecting against electrical shocks or reducing heat loss in buildings.

Other options describe characteristics that are contrary to what defines an insulator. For example, a material that easily conducts heat and electricity is classified as a conductor, while materials that enhance energy transfer would also not qualify as insulators. Furthermore, specifying a material that only conducts heat does not encompass the electrical insulating properties, which are equally important in defining an insulator's role. Thus, the correct answer accurately captures the defining traits of insulators by emphasizing their poor conductivity in both heat and electricity.