The correct representation is (b) — the one showing a double bond (O=O) between two oxygen atoms, as each oxygen (valency 2) shares two pairs of electrons to complete its octet.
Oxygen has 6 valence electrons and needs 2 more to complete its octet. Two oxygen atoms each contribute 2 electrons to form 2 shared pairs → a double covalent bond (O=O). Options showing a single bond or triple bond are incorrect. The correct electron-dot structure must show two shared pairs between the oxygen atoms and two lone pairs on each oxygen.