The pair(s) of diamagnetic ions is(are):
\( \mathrm{La}^{3+},\ \mathrm{Ce}^{4+} \)
\( \mathrm{Yb}^{2+},\ \mathrm{Lu}^{3+} \)
\( \mathrm{La}^{2+},\ \mathrm{Ce}^{3+} \)
\( \mathrm{Yb}^{3+},\ \mathrm{Lu}^{2+} \)
