Refer to Figure 4.6, which shows David's and Celeste's individual supply curves for flower arrangements per week. Assuming David and Celeste are the only producers in the market, what is the market quantity supplied at a price of $20?

The Fed can change the money supply by changing

A) the required reserve ratio. B) marginal income tax rates. C) federal excise taxes. D) unemployment benefits.

An appeal to people's sense of civic or moral responsibility will ________ the free-rider problem and lead to a ________ level of contribution to the public good.

A. increase; smaller B. increase; larger C. reduce; smaller D. reduce; larger