Answer:
D. Ionic bond
Explanation:
First some definitions: ionic bonds always have metals that transfer electrons. Covalent bonds are between nonmetals that share electrons. (Sharing is caring!)
Li is a metal, so right off the bat we know this is not a covalent bond. However, it's not a metal, so we can cross off C as well. The phrase "paired bond" isn't common, so we know the answer must be D. ionic bond.
And in this bond, Li's electrons will transfer to O to make both have a full valence shell. (As opposed to covalent bonds, which share electrons, not transfer completely.)
