An increase in which of the following would cause an increase in aggregate supply?

If an industry were perfectly competitive, the four-firm concentration ratio would be close to ________ and the Herfindahl-Hirschman index would be close to ________

A) 0; 0 B) 0; 100 C) 100; 0. D) 100; 100.

Over the past 100 years, as the U.S. economy's income has grown,

a. tax rates have decreased, while tax revenues have increased. b. tax rates have increased, while tax revenues have decreased. c. both tax rates and tax revenues have increased. d. both tax rates and tax revenues have decreased.