What is the characteristic of points outside the production possibility frontier?

Points outside the production possibility frontier (PPF) represent combinations of goods and services that cannot be produced with the available resources and technology. These points are deemed "unattainable" because they lie beyond the maximum output that the economy can produce given its current resource constraints.

The PPF itself reflects the trade-offs and opportunity costs involved in the production of various goods. When looking at points on the curve, they illustrate efficient production levels, where resources are optimally allocated. Points inside the PPF indicate inefficiency since they suggest that resources are not being utilized to their fullest potential. Therefore, any point that lies outside this frontier is not feasible, making "unattainable" the correct characterization.