The species having diamagnetic nature and bond order 1.0 is

For given molecules or ions, we will find the bond order and magnetic character based on their molecular orbital diagrams.

From the above table, we should conclude that the species ${\mathrm{O}}_2^{-2}$ has the bond order is 1 and it is diamagnetic nature. In  ${\mathrm{O}}_2^{-2}$ ion, there are no unpaired electrons of it’s the molecular orbitals.