$\sigma 1 s^{2} \sigma^{*} 1 s^{2} \sigma 2 s^{2} \sigma^{*} 2 s^{2} \sigma 2 p_{z}^{2} \pi 2 p_{x}^{2}=\pi 2 p_{y}^{2} \pi * 2 p_{x}^{1}=\pi * 2 p_{y}^{1}$

When electron is added in $O _{2}$ to form $O _{2}^{-},$ the added electron goes to $\pi * 2 p_{x}$ or $\pi * 2 p_{y}$

Thus, option $( C )$ is correct.