Which one of the following order represents the correct sequence of the increasing basic nature of the given oxides ?

Question

( A ) $Na_2O < K_2O < MgO < Al_2O_3$
( B ) $MgO < K_2O < Al_2O_3 < Na_2O$
( C ) $Al_2O_3 < MgO < Na_2O < K_2O$
( D ) $ K_2O < Na_2O < Al_2O_3 < MgO $