(N/A) The alkylation of benzene is an example of an electrophilic aromatic substitution reaction.
The mechanism proceeds in two main steps:
Step-$1$: This is the rate-determining step (slow step). The electrophile (carbocation,$R^+$) attacks the benzene ring to form a resonance-stabilized carbocation intermediate known as the $\sigma$-complex (arenium ion).
Step-$2$: This is a fast step. The $\sigma$-complex loses a proton $(H^+)$ to a base (like $AlCl_4^-$) to restore the aromaticity of the ring,resulting in the formation of alkylbenzene.
The resonance structures of the $\sigma$-complex are represented by $(A)$,$(B)$,and $(C)$,and the hybrid structure is $(D)$.