A compound $\mathrm{A}$ with molecular formula ${\mathrm{C}}_{10}{\mathrm{H}}_{13}\mathrm{C}\mathrm{l}$, gives a white precipitate on adding silver nitrate solution. $\mathrm{A}$ on reacting with alcoholic $\mathrm{KOH}$ gives compound $\mathrm{B}$ as the main product. $\mathrm{B}$ on ozonolysis, gives $\mathrm{C}$ and $\mathrm{D}$. $\mathrm{C}$ gives Cannizaro reaction, but not aldol condensation. $\mathrm{D}$ gives aldol condensation, but not Cannizaro reaction. $\mathrm{A}$ is