What are the leading theories in the 1960s, 1970s and 1980s respectively? Select the correct sequence.
A．Behaviorism, Structuralism, Interlanguage and Transfer theories
B．Structuralism, Behaviorism, Interlanguage and Transfer theories
C．Interlanguage and Transfer theories, Structuralism, Behaviorism
D．Transfer theories, Structuralism and Interlanguage, Behaviorism