Stability of the complex depends on

The correct statement about the complex of cobalt whose structure is given below is

I. Primary valency of metal is $6$, while secondary valency is zero.

II. Primary valency of metal is $3$, while secondary valency is $6$

III. Primary valency of metal is $6$, while secondary. valency is $3$

IV. Chemical formula of compound is $\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_3{\mathrm{Cl}}_3\right]$