According to the Keynesian Aggregate Expenditures Model, Equilibrium and Full

According to the Keynesian aggregate expenditures model, equilibrium and full employment:

A) always occur at the same income level of real GDP.
B) may differ, but there is an automatic mechanism that directs the economy toward full-employment equilibrium.
C) could never occur at the same level of real GDP.
D) do not necessarily occur at the same level of real GDP.