Secondary valences of the following complexes based on their reactions with excess $\mathrm{AgNO}_3$ are $\begin{array}{llc}\begin{array}{l}\text { Formula of the } \\ \text { complexes }\end{array} & \begin{array}{c}\text { Moles of AgCl precipitated } \\ \text { per mole of complex }\end{array} \\ \text { (I) } \mathrm{CoCl}_3 \cdot 6 \mathrm{H}_2 \mathrm{O} & 3 \\ \text { (II) } \mathrm{NiCl}_3 \cdot 6 \mathrm{H}_2 \mathrm{O} & 2 \\ \text { (III) } \mathrm{Co}\left(\mathrm{SO}_4\right) \mathrm{Br}^2 5 \mathrm{NH}_3 & 1 \\ \end{array}$ I II III

• A

  4 6 6
• B

  6 4 4
• C

  6 4 6
• Correct answer
  D

  6 6 6

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