Answer
A BaCO3
Work Step by Step
The compound BaCo3 contains both ionic and covalent bonds. As the bond in between Ba2+ and Co3(2-) is an ioninc bond and there is a covalent bond in between the carbon and oxygen of CO3(2-). MgCl2 and BaO only contain ionic bond and H2S and SO4(2-) only contain covalent bonds.