One mole of the complex compound Co(NH3)5 Cl3 gives 3 moles of ions on dissolution in water. One mole of the same complex reacts with two moles of AgNO3 solution to yield two moles of AgCl (s). The structure of the complex is
a. [Co(NH3)3 Cl3] . 2NH3
b. [Co(NH3)4 Cl2]Cl . NH3
c. [Co(NH3)4 Cl]Cl2 . NH3
d. [Co(NH3)5 Cl]Cl2