Nineteenth century art critics judged art by the realism of its method of representation. ... It is one of the permanent gains of the aesthetic revolution of the twentieth century that we are rid of this type of aesthetics.
From the last sentence, you can infer that the 20th century got rid of "this type of aesthetics" (judging work of art by its realistic representation).
(A) which is about "deemphasizing" realistic representation renders itself equivalent to the above interpretation.