Identify the correct statement regarding the stability of oxidation states in the first transition series.

1. A.${\text{Mn}}^{2+}$ is more stable than ${\text{Fe}}^{2+}$ towards oxidation to the $+3$ state.
2. B.${\text{Ti}}^{4+}$ is less stable than ${\text{Ti}}^{3+}$.
3. C.${\text{Sc}}^{3+}$ is unstable in aqueous solution.
4. D.${\text{Cu}}^{2+}$ is less stable than ${\text{Cu}}^{+}$ in aqueous solution.