The correct answer is D: Capacitor. A capacitor is the type of electrical component that consists of conductive surfaces separated by an insulator. This is the fundamental structure of a capacitor - two conductive plates (surfaces) with an insulating dielectric between them. Capacitors are constructed with two conductive surfaces (plates or foils) separated by an insulating material called a dielectric. The dielectric can be air, paper, plastic, ceramic, or other insulating materials. This structure allows the capacitor to store electrical energy in the electric field between the plates. The capacitance depends on the plate area, distance between plates, and dielectric material. This construction is unique to capacitors.