Here's why:

* Electronegativity is the tendency of an atom to attract electrons towards itself in a chemical bond.

* Oxygen has a higher electronegativity value (3.44) than sulfur (2.58) on the Pauling scale.

* This is because oxygen is smaller than sulfur, meaning its valence electrons are closer to the nucleus and experience a stronger attraction.

* Additionally, oxygen has a greater nuclear charge (more protons) than sulfur, further increasing its pull on electrons.

As a result, in a bond between oxygen and sulfur, oxygen will tend to attract the shared electrons more strongly, making the bond polar.