Which statement best describes an insulator?

An insulator is best described as a material that does not easily carry electric flow. Insulators have tightly bound electrons that do not move freely, which prevents electrical current from passing through them efficiently. This characteristic is essential in electrical engineering and applications, where insulators are used to protect and contain electric currents, ensuring safety and functionality within circuits.

The concept of a material permitting electrical flow with ease pertains specifically to conductors, which are designed to allow electricity to move freely. Meanwhile, high-efficiency conductors are materials like copper or aluminum that facilitate electrical flow very effectively. The option suggesting a substance that only conducts under high pressure does not accurately capture the definition of an insulator, as insulators generally do not become conductive under pressure without specific conditions or alterations.