$AlC{l_3}$ is

Among the following, the correct statement(s) is(are)

$[A]$ $\mathrm{A} 1\left(\mathrm{CH}_3\right)_3$ has the three-centre two-electron bonds in its dimeric structure

$[B]$ $\mathrm{BH}_3$ has the three-centre two-electron bonds in its dimeric structure

$[\mathrm{C}] \mathrm{AlCl}_3$ has the three-centre two-electron bonds in its dimeric structure

$[D]$ The Lewis acidity of $\mathrm{BCl}_5$ is greater than that of $\mathrm{AlCl}_5$

Aluminium $(III)$ chloride forms a dimer because

Hydrogen gas will not reduce

Given below are two statements:

Statement $I$: Group $13$ trivalent halides get easily hydrolyzed by water due to their covalent nature.

Statement $II$: $\mathrm{AlCl}_3$ upon hydrolysis in acidified aqueous solution forms octahedral $\left[\mathrm{Al}\left(\mathrm{H}_2 \mathrm{O}\right)_6\right]^{3+}$ ion.

In the light of the above statements, choose the correct answer from the options given below :

In which of the following reaction, the hybridisation of the central atom changes from $sp^2$ to $sp^3$ ?