Opportunity Cost: The opportunity cost refers to the value of the next best alternative foregone when making a choice. For example, if an economy decides to produce more cars, it must give up producing some other goods, such as computers.
Efficiency: Efficiency means using resources in the best possible way to maximize output. On the production possibilities curve, points on the curve represent efficient use of resources, while points inside or outside the curve represent inefficiency.
Economic Growth: Economic growth refers to an increase in an economy's ability to produce goods and services over time. It is represented by an outward shift of the production possibilities curve, indicating that more goods can be produced with existing resources and technology.