The size of Hafnium is almost similar to that of zirconium this is due to

Read the following statements and choose the correct option.
(i) $\mathrm{f}$-block elements of $6^{\text{th }}$ period are called lanthanoids.
(ii) $\mathrm{f}$-block elements of $7^{\text{th }}$ period are called actinoids.

Given below are two statements :

Statement I : The $\mathrm{E}°$ value of ${\mathrm{Ce}}^{4+}/{\mathrm{Ce}}^{3+}$ is $+1.74 \mathrm{V}$

Statement II : Ce is more stable in ${\mathrm{Ce}}^{4+}$ state than ${\mathrm{Ce}}^{3+}$ state.

In the light of the above statements, choose the most appropriate answer from the options given below: