Aryl halides are extermely less reactive towards nucleophilic substitution. Predictand explain the order of reactivity of the compounds towards nucleophilic substitution.

Explanation

Aryl halides are less reactive towards nucleophilic substitution reaction. Presence of electron withdrawing group at ortho and para position increases the stability of intermediates and hence increases the reactivity of aryl halides towards nucleophilic substitution reaction
Now, more the number of EWG at ortho and para position, higher will be the reactivity of aryl halide. Compound (III) has three EWG so, it is most reactive and compound (I) has only one EWG So, it is least reactive. S0, the order af reactivity is `(I)lt(II)lt(II)`