Nuclephilic substitution reaction is given by those compounds which have nucleophilic groups as leaving groups. The weaker the basicity of a group of the substrate, the better is its leaving ability.
In nucleophilic substitution reactions, the basicity of leaving group should be less than the incoming nucleophilic group. Nucleophilc substitution reaction at `sp^(3)` -hybridised carbon is either bimolecular `(S_(N^(2)))` or unimolecular `(S_(N^(1)))`. Bimolecular reaction takes place in single step, involving transition state intermediate. In `S_(N^(2))` reaction is preferred if the compound has less steric hindrance.
Unimolecular `(S_(N^(2)))` reaction involves two steps and carbonium ion intermediate. Optically active substrates give recemic mixture in these reactions.
Which compound will give Walden inversion in `S_(N^(2))` reaction?

Options

A. `CH_(3)CH_(2)Br`
B. `CH_(3)-CHD-Br`
C. `CH_(3)-Br`
D. `C_(6)H_(5)CH_(2)CH_(2)Cl`