The correct answer is D. PbSO4.
During discharge, the active material of the positive plate is changed from PbO2 to PbSO4, and the active material of the negative plate is changed from Pb to PbSO4. This reaction produces electricity, which is used to power devices.
PbO2 is a black, crystalline solid. It is the active material of the positive plate in a lead-acid battery. When a lead-acid battery is discharged, PbO2 is reduced to PbSO4.
Pb is a soft, silvery-white metal. It is the active material of the negative plate in a lead-acid battery. When a lead-acid battery is discharged, Pb is oxidized to PbSO4.
PbSO4 is a white, crystalline solid. It is the product of the discharge reaction in a lead-acid battery. When a lead-acid battery is recharged, PbSO4 is converted back to PbO2 and Pb.