Which one of the following is called amphoteric solvent

$\underset{\text{ Acid }}{{\mathrm{H}}_2\mathrm{O}}\to {\mathrm{H}}^{+}+{\mathrm{OH}}^{-}$ [Acid due to donation of proton]

$\underset{\text{ Base }}{{\mathrm{H}}_2\mathrm{O}+{\mathrm{H}}^{+}}\to {\mathrm{H}}_3{\mathrm{O}}^{+}$ [Basic due to gaining of proton]