In which of the following ionization processess, the bond order has increased and the magnetic behaviour has changed?

Question

$\begin{array}{1 1} (a)\;C_2 \to C_2^+ \\ (b)\;NO \to N_O^+ \\ (c)\;O_2 \to O_2^+ \\ (d)\;N_2 \to N_2^+ \end{array}$