Which of the following is paramagnetic?

Solution :
$$O_2^ - \left( {17{e^ - }} \right) - K\,K\,\sigma 2{s^2}{\sigma ^*}2{s^2}\sigma 2p_x^2,\left\{ {\pi 2p_y^2 = \pi 2p_z^2,\left\{ {{\pi ^*}2p_y^2 = {\pi ^*}2p_z^1} \right.} \right.$$
Thus, $$\,O_2^ - \,$$  has one unpaired electron; hence it is paramagnetic. Other species have no unpaired electron.
All of them have 14 electrons.