Acidic ferric chloride solution on treatment with excess of potassium ferrocyanide gives a Prussian blue coloured colloidal species. It is:

• A

  $\mathrm{HFe}\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$
• B

  ${\mathrm{K}}_5\mathrm{Fe}{\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}_2$
• C

  ${Fe}_4{\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]}_3$
• Correct answer
  D

  $\mathrm{KFe}\left[\mathrm{Fe}(\mathrm{CN}{)}_6\right]$

Hence, the correct answer is option: 'D'.