Which one of the following complexes is an outer orbital complex?

Outer orbital complexes use the $(n)d$ orbitals for hybridization (usually $s{p}^3{d}^2$).$[\text{Ni}({\text{NH}}_3{)}_6{]}^{2+}$: ${\text{Ni}}^{2+}$ is $d^8$. For an octahedral complex, it has no empty inner $d$ -orbitals available even after pairing. It must use $4d$ orbitals, making it $s{p}^3{d}^2$ (outer orbital octahedral).${\text{CN}}^{-}$ is a strong field ligand and usually forms inner orbital complexes with metals like $\text{Fe}$ and $\text{Mn}$ ($d^{2}s{p}^3$).$[\text{Co}({\text{NH}}_3{)}_6{]}^{3+}$ is a classic inner orbital $d^{2}s{p}^3$ complex.