From the Classical Perspective,a Decrease in Output During a Recession

From the classical perspective,a decrease in output during a recession is a result of

A) firms voluntarily supplying fewer goods and services in the marketplace.
B) a greater quantity of goods and services supplied than is the quantity demanded for these goods and services.
C) the decrease in the overall level of production due to those firms which were forced to shut down.
D) the decline in availability of factors of production that naturally occurs at the onset of a recession.