The Economy's AS Curve Is Often Assumed to Be Relatively

The economy's AS curve is often assumed to be relatively flat at low levels of real GDP.The underlying reasoning is that

A) consumer demand for most goods tends to be non-responsive to price when output is low.
B) consumer demand for most goods tends to be very responsive to price when output is low.
C) at low levels of output,firms are faced with unused capacity and thus can increase output without significantly increasing their costs.
D) the price level is constant.
E) profits are normally high in this section of the AS curve,so firms are willing to expand output.