The long run aggregate supply curve is:
A) Upward-sloping and becomes steeper at output levels above the full-employment output.
B) Upward-sloping and becomes flatter at output levels above the full-employment output.
C) Downward-sloping and becomes steeper at output levels above the full-employment output.
D) Downward-sloping and becomes flatter at output levels above the full-employment output.