$\begin{matrix} (A) K_2O < Na_2O < Al_2O_3 < MgO \\ (B) Al_2O_3 < MgO < Na_2O < K_2O \\ (C) MgO < K_2O < Al_2O_3 < Na_2O \\ (D) MgO < K_2O < Na_2O < Al_2O_3 \end{matrix}$
