Among the following, the lanthanoid that commonly shows the $+4$ oxidation state in addition to $+3$ is

$\mathrm{Ce}{}^{4+}$ has the empty $4f^0$ configuration, so cerium readily shows +4 (for example in $\mathrm{CeO}{}_2$). $\mathrm{La}{}^{3+}$, $\mathrm{Gd}{}^{3+}$ and $\mathrm{Lu}{}^{3+}$ already have $4f^0$, $4f^7$ and $4f^{14}$ and do not form +4 ions.