Which of the following displays a non-polar covalent bonding?

Chlorine molecule displays a non-polar covalent bonding. In a nonpolar covalent bond, electrons are shared equally and there is no sharp dividing line between polar and nonpolar and as per thumb rule the Non polar covalent would be considered for if the electronegativity difference between bonding atoms is less than 0.5 and hence anything greater than this value will be considered for anything but nonpolar bond.