Select the correct IUPAC names.

First: cation charge $+1$ gives Co(III). Second: $x-2=-1$ gives Au(I), and the anion takes -ate (aurate). Third: the cation is $+2$ (Cu(II)) and the anion $2-$ (Pt(II)), with the cation named first. The fourth is an anion, so it must be hexacyanidoferrate(III).