All of the following are examples of goods for which external costs commonly exist EXCEPT

The advantage of a system of fixed exchange rates over one where exchange rates are flexible is that

a. the government gains more control over the economy. b. floating exchange rates impose risks on importers and exporters from unpredictable exchange rates. c. exchange controls become unnecessary. d. fiscal and monetary policy can focus more on domestic conditions.

Refer to the diagrams. The firm:

A.  has a principal-agent problem.
B.  has a constant marginal resource cost of $5.
C.  has a marginal resource cost that exceeds the wage rate for each worker.
D.  will fail to maximize profits if it hires 5 workers.