Aldehyde And Ketone

An organic compound, ' $A$ ' with molecular formula $\mathrm{C}_8 \mathrm{H}_8 \mathrm{O}$ on reaction with $\mathrm{I}_2 / \mathrm{KOH}$ gives salt of carboxylic acid ' $B$ ' and a halo-compound ' $C$ '. Compound ' $C$ ' on the reaction with silver powder gives ' $D$ '. The structures of ${ }^{\prime} A^{\prime}$ and ' $D^{\prime}$ are