【单选题】

According to the passage, the specialization of art and theory has tended to
A．(A) reduce the level of control artists have over artistic institutions

B．(B) increase the usefulness of creating a unifying artistic vocabulary
C．(C) permit a greater level of development of knowledge concerning both
D．(D) curtail interactions and establish false boundaries between the two fields
E．(E) complicate the educational process of artists in an unfortunate manner