How do you determine what molecule would have the most polar bond from a list of molecules?
Check the electronegativities of the atoms involved in each bond. The greatest difference in electronegativity will correspond to the most polar bond.
The elecronegativity of an element is a measure of the tendency of that atom to attract the bonding electrons toward itself. Since electronegativity is based on the charge on the atom's nucleus and the location of it valence shell, we find the most electronegative elements in the upper right corner of the Periodic Table (excluding the noble gases, which do not bond, and therefore cannot be properly evaluated on this scale). The least electronegative elements are found in the lower left of the table.