Among the following the maximum covalent character is shown by the compound:

According to Fajan's rules, covalent character increases with:Small size of cation.Large size of anion.High charge on cation.Pseudo-noble gas configuration.Comparing cations ${\text{Sn}}^{2+}$, ${\text{Al}}^{3+}$, ${\text{Mg}}^{2+}$, ${\text{Fe}}^{2+}$:${\text{Al}}^{3+}$ has the highest charge ($+3$) and a small size. Thus, ${\text{AlCl}}_3$ shows the maximum covalent character.