Which of the following reagents react differently with $\mathrm{HCHO}, {\mathrm{CH}}_{\mathrm{3}}\mathrm{CHO}$ and ${\mathrm{CH}}_{\mathrm{3}}{\mathrm{COCH}}_{\mathrm{3}}$?

The acid $\mathrm{D}$ obtained through the following sequence of reactions is:

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Br}\stackrel{\mathrm{Alc}. \mathrm{KOH}}{⟶}\mathrm{A}\underset{{\mathrm{CCl}}_4}{\overset{{\mathrm{Br}}_2}{\to }}\mathrm{B}\underset{\left(\mathrm{excess}\right)}{\overset{\mathrm{KCN}}{\to }}\mathrm{C}\stackrel{{\mathrm{H}}_3{\mathrm{O}}^{+}}{⟶}\mathrm{D}$