What is a characteristic of a material that does not easily conduct electricity or heat?

An insulator is a material that does not easily conduct electricity or heat. This characteristic is due to its atomic structure, which does not allow free movement of electrons. As a result, insulators are often used in various applications to prevent the flow of electric current or to minimize heat transfer. For instance, materials like rubber, plastic, and glass serve as insulators in electrical wiring to protect against shocks and in thermal applications to keep heat contained.

In contrast, conductors are materials that readily allow electricity or heat to flow through them, typically due to the presence of free electrons. Superconductors are specialized materials that can conduct electricity without resistance under certain conditions but do not fit the general definition of an insulator. A heat sink, on the other hand, is a device designed to dissipate heat from components, often utilizing conductors to draw heat away, rather than being characterized by an inability to conduct heat. Therefore, the defining feature of an insulator is its resistance to the flow of electricity and heat, making it the correct choice.