What type of device is used for storing electrical charge?

A capacitor is the correct answer because it is specifically designed to store electrical charge. It consists of two conductive plates separated by an insulating material, known as a dielectric. When a voltage is applied across the plates, an electric field is created, causing charge to accumulate on the plates. The amount of charge a capacitor can hold is determined by its capacitance, which is measured in farads.

In contrast, a resistor is a passive component that resists the flow of electrical current and dissipates energy as heat, while an inductor stores energy in a magnetic field when electrical current flows through it. A transformer is a device that transfers electrical energy between two or more circuits through electromagnetic induction, typically used to change the voltage levels of alternating current (AC) signals. Thus, they do not function to store electrical charge in the way a capacitor does.