Higher real GDP growth usually causes

A disadvantage of the barter system is that

A. people must produce all their own food, clothing, and shelter. B. the opportunity to specialize is greatly reduced. C. no trade occurs. D. gold is the only unit of account.

What does making decisions "at the margin" mean?

a. that people evaluate how easily a decision can be reversed if problems arise b. that people make those decisions that do not impose a marginal cost c. that people compare the marginal costs and marginal benefits of each decision d. that people always calculate the marginal dollar costs for each decision