Answer:
C
Step-by-step explanation:
It depends on the bonding for an explanation.
If one atom is a metal and one is a non metal it will be ionic. This is because one atom transfers its electron to the other atom giving them both a charge. They will then be bonded due to opposite forces of attraction.
If both atoms are non metals it will be covalent. Electrons pair together in the center of two atoms that have merged together and they share their electrons.
(Makes more sense with diagrams)