What Lesson Emerged from the Occurrence of the Great Depression

Multiple Choice

What lesson emerged from the occurrence of the Great Depression in Canada?  

A)  Potential GDP could be too low to ensure full employment in a capitalist economy. 
B)  Potential GDP could be too low to ensure full employment in a market economy. 
C)  Potential GDP could fall short of full-employment GDP. 
D)  Potential GDP could exceed equilibrium GDP.