Solution

Basic strength decreases from $$\mathrm{La(OH)_{3}}$$ to $$\mathrm{Lu(OH)_{3}}.$$

Configurations of
$$\mathrm{Ce = [Xe] 4f^{1} \,5d^{1} \,6s^{2}\ \ ; \, \implies Ce^{4+} = [Xe]}$$
$$\mathrm{Yb = [Xe] 4f^{14} \,6s^{2}\ \ \ \ \ \ \ \ ; \, \implies Yb^{2+} = [Xe]4f^{14}}$$
$$\mathrm{Lu = [Xe]4f^{14} \,5d^{1} \,6s^{2} \ ; \, \implies Lu^{3+} = [Xe]4f^{14}}$$

$$\implies$$ $$\mathrm{Ce^{4+}, \ Yb^{2+} \ \& \ Lu^{3+}}$$ are diamagnetic in nature.

So, only statement (i) is incorrect.
Hence, Option "B" is the correct answer.