(N/A) The reasons for the low reactivity of aryl halides towards nucleophilic substitution reactions are as follows:
$(a)$ Resonance Effect: In haloarenes, the electron pairs on the halogen atom $(X)$ are in conjugation with the $\pi$-electrons of the ring. Due to resonance, the $C-X$ bond acquires partial double bond character. This makes the cleavage of the $C-X$ bond difficult compared to haloalkanes, where the bond is purely single.
$(b)$ Difference in Hybridization of Carbon Atom in $C-X$ Bond: In haloalkanes, the carbon atom attached to the halogen is $sp^3$ hybridized, whereas in haloarenes, it is $sp^2$ hybridized. The $sp^2$ hybridized carbon has more $s$-character $(33\%)$ compared to $sp^3$ $(25\%)$, making it more electronegative. Consequently, it holds the electron pair of the $C-X$ bond more tightly, resulting in a shorter and stronger bond ($169 \text{ pm}$ in haloarenes vs $177 \text{ pm}$ in haloalkanes), which is harder to break.