The correct answer is insulator. An insulator is a material that has very high resistance to the flow of electric current, which means that it does not easily allow electrical charges to pass through it. This property is essential in various applications where the prevention of current flow is necessary, such as in electrical wiring and electronic devices. Insulators are commonly made from materials like rubber, glass, and plastic.
In contrast, conductors facilitate the flow of electricity due to their low resistance, enabling electric charges to move freely. Semiconductors have a conductivity that is between that of conductors and insulators and can be altered by adding impurities or changing environmental conditions, which allows them to be useful in electronic components like transistors and diodes. Superconductors exhibit zero electrical resistance at very low temperatures, which allows for the lossless flow of current but are not characterized by high resistance under standard conditions. Each of these materials serves distinct purposes in electrical engineering and electronics, with insulators specifically designed to restrain current flow.