Which of the following is not inner transition element?

Statement $\mathrm{I}:$ Nickel $\left(\mathrm{II}\right)$ compounds are thermodynamically less stable than platinum $\left(\mathrm{II}\right)$ compounds in the gaseous phase.

Statement $\mathrm{II}:$ Nickel $\left(\mathrm{IV}\right)$ compounds are thermodynamically more stable than platinum $\left(\mathrm{IV}\right)$ compounds in the gaseous phase..