Answer:
C.) highly polar covalent
Explanation:
The electronegativity value of P and O are 2.1 and 3.5 respectively, with O atom being more electronegative than P atom. The electronegativity difference in the P-O bond is 1.4.
In polar covalent bonds the electronegativity difference between two atoms is between 0.5 and 2.0. In nonpolar bonds the electronegativity difference between the two atoms is less than 0.5. And in ionic bonds the electronegativity difference between the two atoms is greater than 2.0.