Which of the following is paramagnetic?

What are the types of molecular orbitals? Provide a brief explanation.

Arrange the following in the increasing order of their bond order: $O_{2}, O_{2}^{+}, O_{2}^{-}, O_{2}^{2-}$

After understanding the assertion and reason, choose the correct option.
Assertion : In the bonding molecular orbital $(MO)$ of $H_2,$ electron density is increased between the nuclei.
Reason : The bonding $MO$ is $\psi_A + \psi_B,$ which shows destructive interference of the combining electron waves.

For diatomic molecules,the correct statement$(s)$ about the molecular orbitals formed by the overlap of two $2p_z$ orbitals is(are):
$(A)$ $\sigma$ orbital has a total of two nodal planes.
$(B)$ $\sigma^*$ orbital has one node in the $xz$-plane containing the molecular axis.
$(C)$ $\pi$ orbital has one node in the plane which is perpendicular to the molecular axis and goes through the center of the molecule.
$(D)$ $\pi^*$ orbital has one node in the $xy$-plane containing the molecular axis.

If the bond order in $C_2$ is '$x$',then the bond order in $B_2$ and $O_2$,respectively,are