In every economic system, choices must be made because resources are ________ and our wants are ________

The efficient scale of a firm is defined as the point where

A) average total cost is minimized. B) marginal revenue equals marginal cost. C) price equals marginal cost. D) marginal revenue equals zero.

Which of the following is most likely to be an untraded good in a Ricardian two-country, multi-good model?

A) steel B) textiles C) haircuts D) petroleum E) telemarketer services