\( \text{C}_2\text{H}_5\text{Br} \xrightarrow{\text{alc. KOH}} \text{A} \xrightarrow[\text{CCl}_4]{\text{Br}_2} \text{B} \xrightarrow[\text{Excess}]{\text{KCN}} \text{C} \xrightarrow[\text{Excess}]{\text{H}_3\text{O}^+} \text{D}\)
Acid D formed in above reaction is: