A device used to store an electric charge, consisting of one or more pairs of conductors separated by an insulator is known as-
A. Capacitor
B. Inductor
C. Resistor
D. Battery

Hint: Capacitor, electrical energy storage unit composed of two conductors in close proximity and separated from one another. The parallel-plate condenser is a clear example of such a storage unit.

Complete Step-by-Step solution:
If the positive charges of total charge + Q are deposited on one of the applied conductors and an equivalent amount of negative charge −Q on the second conductor is deposited, the condenser is supposed to have a charge Q.
There are many significant applications for the capacities. For example, they are used in electronic systems so that stored information in powerful computer memories is not lost during a temporary electrical power failure; the electrical energy stored in these condensers retains the information during the temporary power loss. Capacitors play an even greater function as filters for diverting spurious electrical signals and thus preventing damage to sensitive components and circuits caused by electrical surges.
Thus, we can say that - A system used to store electric charge is known as a capacitor, consisting of one or more pairs of conductors separated by an insulator.
An inductor, also known as a coil, choke or reactor, constitutes a passive two-terminal electrical portion that retains energy as electrical force passes through it in a magnetic field. Usually an inductor is a shielded filament wrapped in a circle around a heart.

Note: A capacitor is a system used for storing charges in a series current. A capacitor operates on the idea that a conductor's capacitance increases significantly when an earthed conductor is placed close to it. Therefore, a capacitor has two plates, apart by a length with equal but opposite charges.