Chemical Bonding And Molecular Structure

Which of the following two molecular species are Diamagnetic in nature?

\([\mathrm{A}]=\mathrm{O}_2^{-} \quad[\mathrm{B}] .=\mathrm{N}_2^{+} \quad[\mathrm{C}]=\mathrm{C}_2 \quad[\mathrm{D}]=\mathrm{O}_2{ }^{2-}\)