Acidic ferric chloride solution on treatment with excess of potassium ferrocyanide gives a Prussian blue coloured colloidal species. It is:
A. K 5Fe[Fe(CN) 6] 2
​B. HFe[Fe(CN) 6 ]
C. Fe 4[Fe(CN) 6 ] 3
​D. KFe[Fe(CN)6_]