Which one of the following ions exhibits d-d transition and paramagnetism as well?

- ${\text{CrO}}_4^{2-}$ and ${\text{Cr}}_2{\text{O}}_7^{2-}$: $\text{Cr}$ is in $+6$ state ($d^0$). Color is due to Charge Transfer, not d-d transition. Diamagnetic ($n=0$).${\text{MnO}}_4^{-}$: $\text{Mn}$ is in $+7$ state ($d^0$). Color is Charge Transfer. Diamagnetic.${\text{MnO}}_4^{2-}$ (Manganate ion): $\text{Mn}$ is in $+6$ state. Configuration is $[Ar]3d^1$. Since it has one unpaired electron, it is paramagnetic and can undergo d-d transitions.