The covalent alkaline earth metal halide is
Alkaline earth metals contain bi positive ions is the compounds here -
i. charge on cation ire +2 is constant
ii. Halide present is also constant
So, the covalent character depends on the sire of alkaline earth metal. As we more down the group, size of metal ion increases.
So, readily forms covalent compounds.
Hence option 4 is correct.