The acid D obtained through the following sequence of reactions is:
`C_(2)H_(5)Br overset(Alc. KOH)rarrA overset(Br_(2))underset(C Cl_(4))rarrBoverset(KCN)underset((excees))rarrCoverset(H_(3)O^(+))rarr`
A. Succinic acid
B. Malonic acid
C. Maleic acid
D. Oxalic acid