Final answer:
Economic efficiency is achieved when an economy maximizes the benefits from its scarce resources, as shown by choice 'b' in the multiple-choice question.
Step-by-step explanation:
The concept in question is economic efficiency, which is essential in understanding how an economy utilizes its scarce resources. The correct answer to the multiple-choice question is: b. is achieved when the economy gets the most out of its scarce resources. This definition aligns with the third theme of economic efficiency, which focuses on maximizing the benefit derived from scarce resources. In the context of a production possibilities frontier, economic efficiency implies that the economy is operating in a way where it is impossible to produce more of one good without reducing the output of another good, indicating productive efficiency. When considering personal or social choices, allocative efficiency is displayed when the choice reflects the preferred combination of goods and services.