Explanation: A lead-acid storage battery operates through an electrochemical process. Energy is stored in the chemical bonds of the materials within the battery: lead plates (lead and lead dioxide) and an electrolyte (sulfuric acid). When the battery is charged, electrical energy is converted into chemical potential energy, transforming the chemical composition of these materials. When discharged, these chemicals react, releasing the stored chemical energy as electrical current. This reversible chemical reaction is the core principle of how a battery functions as a power source for radios and other electronic devices. Mechanical energy relates to motion or position, heat energy is thermal, and light energy is electromagnetic radiation; none of these are the primary form of energy stored within a battery's chemical structure. While some heat might be generated during operation, it's not the stored form of energy.