@Nishant-Thakre During discharging of a lead storage battery, sulfuric acid is consumed and water is produced. Lead sulphate is formed at both electrodes. Since sulfuric acid is consumed, the concentration of H+ ions and the density of the electrolytic solution decreases.
Hence the right option is A
But in the rxns pbo2 is also consumed I think
@Nishant-Thakre yeah u have a valid doubt ...but since they have mentioned about concentration ....I guess they are concerned about the electrolytic solution .....