An octahedral complex $\mathrm{K}{}_x[\mathrm{CrF}{}_6]$ has chromium in the +2 or +3 state, F- is a weak-field ligand, and the spin-only moment is 4.90 BM. The formula and name are

1. A$\mathrm{K}{}_4[\mathrm{CrF}{}_6]$, potassium hexafluoridochromate(III)
2. B$\mathrm{K}{}_3[\mathrm{CrF}{}_6]$, potassium hexafluoridochromate(II)
3. C$\mathrm{K}{}_4[\mathrm{CrF}{}_6]$, potassium hexafluoridochromate(II)
4. D$\mathrm{K}{}_3[\mathrm{CrF}{}_6]$, potassium hexafluoridochromate(III)