Which of the following ions will exhibit color in aqueous solutions?

The ions will exhibit color in aqueous solution is ${\mathrm{Ti}}^{3+}$.

In aqueous solution, only ${\mathrm{Ti}}^{3+}$ shows color. The existence of unpaired electrons is a need for the$\mathrm{d}-\mathrm{d}$ (or$\mathrm{f}-\mathrm{f}$) transition to produce color. Therefore, the only material to show color in aqueous solution is ${\mathrm{Ti}}^{3+}$.