Economic Theorists Expanded on the Keynesian Aggregate Supply Model in the Late

Economic theorists expanded on the Keynesian aggregate supply model in the late 1940s, broadening it into a three-part aggregate supply curve. Which of the following best describes that three-part supply curve?

A) A flat initial segment, followed by a modestly upward-sloping middle segment until full-employment GDP is reached, and finally a more steeply upward-sloping segment beyond full-employment GDP
B) A flat initial segment, followed by an upward-sloping middle segment until full-employment GDP is reached, and finally a vertical segment at full-employment GDP
C) A flat initial segment until full-employment is reached, followed by a vertical segment at full-employment GDP, and finally followed by another flat segment once the full-employment price level is reached
D) An upward-sloping initial segment, followed by an upward-sloping segment until full-employment GDP is reached, and finally followed by another flat segment beyond full-employment GDP