A Country's Production Possibilities Curve Is Concave to the Origin

Multiple Choice

A country's production possibilities curve is concave to the origin (i.e. ,bowed out from the origin) because

A) of the principle of scarcity.
B) the production of one good is expanded by first employing those resources with an absolute advantage.
C) the production of one good is expanded by first employing those resources with the lowest opportunity cost.
D) there is a trade off that requires a decrease in the production of one good in order to increase the production of the other good.
E) of the principle of absolute advantage.