Which will undergo fastest `S_(N)2` substitution reaction when treated with NaOH?

Options

A. `H_(5)C_(2)-undersetunderset(H)(|)oversetoverset(CH_(3))(|)(C)-Br`
B. `CH_(3)-undersetunderset(CH_(3))(|)oversetoverset(CH_(3))(|)(C)-Br`
C. `H-undersetunderset(C_(2)H_(5))(|)oversetoverset(CH_(3))(|)(C)-Br`
D. `H-undersetunderset(Br)(|)oversetoverset(H)(|)(C)-CH_(2)-CH_(2)-CH_(3)`

Answer

D

Explanation

Primary alkyl halides undergo bimolecular nucleophilic substitution most readily.