Historically, which of the following has had the highest average annual rate of return?

If the price of a firm's output rises, its

A) marginal product of labor increases. B) value of marginal product decreases. C) demand for labor increases. D) demand for labor decreases.

Permanent resource price differentials are caused by

a. differences in resource quality b. differences in the time and training required to perform the job c. differences in nonmonetary aspects of the job d. a lack of resource mobility e. all of the above