The answer is A, Nitrogen and oxygen have an electronegativity of 0.5, so the bond is polar covalent, with oxygen pulling the electrons toward it.
Electronegativity is defined as, a value that describes the relative strength with which an atom of an element attracts electrons to itself in a chemical bond. Moreover, electronegativity can be used to define a bond.
A electronegativity of 0.5-1.7 is determined to be a polar covalent bond, thus the bonds in nitrate is polar covalent.
We know that electronegativity increases on the periodic table across a period, but decreases down a group. Thus, oxygen has a greater electronegativity than nitrogen.
