When a economy is at full employment the production possibilites frontier illustrates which principle of economics?

When an economy is at full employment, the production possibilities frontier (PPF) illustrates the principle of opportunity cost. This principle highlights that producing more of one good requires sacrificing the production of another good, as resources are fully utilized. The PPF represents the maximum output combinations of two goods, demonstrating that any point on the curve indicates efficient resource allocation, while points inside the curve indicate inefficiencies. Thus, the PPF reflects the trade-offs inherent in economic decision-making when resources are fully employed.