Which of the folloeing reaction is most common among the alkyl halide and why

a, nucleophilic addition

b. nucleophilic substitution

c. electrophilic addition

d. electrophilic substitution

Please explain briefly.

b.nucleophilic substitution

In alkyl halodes, the halogen atom is attached to an sp³ hybridised carbon atom while in haloarenes, it is attached to an sp² hybridised carbon atom. Since an sp² hybridised carbon has more s-character than sp³ hybridised carbon, the haloarene is more electronegative than the haloalkane. As a result, the neucleophile could attack on less electronegative haloalkanes C-X bonds and thus it becomes more reactive.