The 6-coordinate radii (in pm) of some trivalent ions are $\mathrm{Dy}{}^{3+}$ 91.2, $\mathrm{Ho}{}^{3+}$ 90.1, $\mathrm{Er}{}^{3+}$ 89.0, $\mathrm{Lu}{}^{3+}$ 86.1 and $\mathrm{Y}{}^{3+}$ 90.0. Yttrium therefore most closely resembles which lanthanoid ion in size (and in its chemistry and mineral associations)?

1. A$\mathrm{Er}{}^{3+}$
2. B$\mathrm{Ho}{}^{3+}$
3. C$\mathrm{Lu}{}^{3+}$
4. D$\mathrm{Dy}{}^{3+}$