Two lanthanoids show anomalously large metallic radii compared with their neighbours, because they use only two electrons per atom in metallic bonding, retaining $4f^7$ and $4f^{14}$ cores respectively. They are

1. A$\mathrm{Eu}$ and $\mathrm{Yb}$
2. B$\mathrm{Ce}$ and $\mathrm{Pr}$
3. C$\mathrm{Gd}$ and $\mathrm{Lu}$
4. D$\mathrm{La}$ and $\mathrm{Ce}$