In the circular flow model, households earn their incomes in the:

Along a perfectly competitive industry's long-run supply curve

A) economic profits are positive. B) economic profits are zero. C) entrepreneurs earn an above-average rate of return. D) the number of firms is constant.

The demand curve for coffee shifts

a. only when income changes. b. when a determinant of the demand for coffee other than the price of coffee changes. c. when the price of coffee changes. d. Both b and c are correct.