Explanation
To know whether the bond is polar or not, the electronegativity difference should be 0.4 or less, if it is more than 0.4 the bond is non-polar, and if it is more than 1.8, the bond is ionic.
NaCl does NOT have a polar covalent bond, the electronegativity of the bond is 3.16-0.93 = 2.2, this bond is ionic.
O2 is a diatomic molecules, thus non-polar
Na is a single element, there is no bond
NO is polar because the electronegativity difference is 3.44 - 3.04 = 0.4
Answer
D. NO
