IUPAC name of $K_3[Fe(CN)_6]$ is

Question

$\begin{array}{1 1}(a)\;\text{Potassium of ferrocynade}\\(b)\;\text{Potassium of ferricynide}\\(c)\;\text{Potassium hexa cyanoferrate(II)}\\(d)\;\text{Potassium hexa cyanoferrate(III)}\end{array}$