QUESTION $13$

The negative slope of the PPC directly illustrates which of the following:

Ircinscript

a$.$ that a country can relocate factors between the production of different goods and services

b$.$ that a country faces opportunity cost when making production$-$related decisions

c$.$ that a country has fixed rates of productivity associated with producing goods and services

d$.$ that a country is incapable of producing outside of their PPC

e$.$ that a country can only achieve higher levels of consumption through increases in potential output