The "Production Possibilities Frontier" illustrates Question 14 options: D.All the listed answers are correct A. The economic concept of "scarcity" as combinations of goods and services beyond the frontier are unattainable, all else being equal. B. The economic concept of "scarcity" as combinations of goods and services on the frontier are unattainable, all else being equal. C. The economic concept of "scarcity" as combinations of goods and services inside the frontier are unattainable, all else being equal