ANS:B - Battery

There are many such devices, but the simplest one is a battery. In a battery, a chemical reaction involving the electrolyte (battery fluid) carries ions (charged particles) from one terminal to the other. This flow of charge produces an electric current. For example, in a lead-acid battery (Example: A car battery) on the anode (+), lead sulfate reacts with water to form sulfuric acid and lead oxide, while liberating two electrons. These electrons travel through the electric circuit. On the cathode (-), the lead sulfate absorbs the electrons and creates elemental lead and sulfuric acid.