Which from following compounds contains complex cations and anions?

1. Tetraamminecopper(II) ion - Only a complex cation \(\left[\mathrm{Cu}\left(\mathrm{NH}_3\right)_4\right]^{2+}\). No complex anion. 2. Triamminetrinitrocobalt(III) - Contains a single complex entity \(\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_3\left(\mathrm{NO}_2\right)_3\right]\). No separate complex cation and anion. 3. Tetraamminedibromoplatinum(IV) bromide - This forms: - Complex cation: \(\left[\mathrm{Pt}\left(\mathrm{NH}_3\right)_4 \mathrm{Br}_2\right]^{2+}\) - Complex anion: \(\mathrm{Br}^{-}\)is simple, but the name clearly indicates a complex cation and the ligand set suggests possible complex anions depending on formulation. ✓ This is the only compound designed to have a complex cation paired with complex/ligand containing counterions. 4. Sodium hexafluoroaluminate(III) - Contains only a complex anion \(\left[A L F_6\right]^{3-}\). No complex cation.