Refer to the scenario above. What is Sarah's opportunity cost of producing one greeting card?

Income equality has

A) decreased in the United States as manufacturing has increased. B) narrowed within countries but increased across countries. C) increased within countries but has narrowed across countries. D) not changed in the advanced economies over the past 50 years. E) increased in developing economies as manufacturing has decreased.

A basic principle of economics is that a country's standard of living depends on its

a. quantity of physical capital. b. abundance of natural resources. c. ability to produce goods and services. d. ability to thrive economically without having to interact with other countries.