Explanation

(d)
$N_{2}(7 + 7 = 14) = \sigma 1s^{2},\sigma^{*}1s^{2},\sigma 2s^{2},\sigma^{*}2s^{2},\pi 2p_{x}^{2} \approx \pi 2p_{y}^{2},\sigma 2p_{\mathcal{z}}^{2}$
Bond order $= \frac{10 - 4}{2} = 3$
$N_{2}^{+}(7 + 7 - 1 = 13) = \sigma 1s^{2},\sigma^{*}1s^{2},\sigma 2s^{2},\sigma^{*}2s^{2},\pi 2p_{x}^{2}$
$= \pi 2p_{y}^{2},\sigma 2p_{\pi}^{1}($paramagnetic)
Bond order $= \frac{9 - 4}{2} = 2.5$
Since, $N_{2}^{+}$has less bond, then $N - N$bond gets weak
$O_{2}(8 + 8 = 16) = \sigma 1s^{2},\sigma^{*}1s^{2},\sigma 2s^{2},\sigma^{*}2s^{2},\sigma 2p_{\mathcal{z}}^{2},\pi 2p_{x}^{2} \approx \pi 2p_{y}^{2},\pi^{*}2p_{x}^{1} \approx \pi^{*}2p_{y}^{1}$
Bond order $= \frac{10 - 6}{2} = 2$
$O_{2}^{+}(8 + 8 - 1 = 15) = \ \sigma 1s^{2},\sigma^{*}1s^{2},\sigma 2s^{2},\sigma^{*}2s^{2},\sigma 2p_{\mathcal{z}}^{2},\pi 2p_{x}^{2} \approx \pi 2p_{y}^{2},\pi^{*}2p_{x}^{1}$
Bond order $= \frac{10 - 5}{2} = 2$.5
Thus, in the formation of $O_{2}^{+}$from $O_{2},\$paramagnetism decreases but the bond order increases