An example of a public good is a flood control project that protects all the homes and properties near a river

What did Robert Gilpin mean when he wrote that modern realists know little about international politics that Thucydides did not know in the fifth century BCE?

a. Compared to those times, the twentieth century had been a revolutionary period. b. The world still revolved around political ideologies, theories, and arguments. c. Much had changed, but the underlying nature of international politics had not changed. d. Modern realists had not advanced the body of knowledge in political science very much.

From 1900 to 2013 real GDP per person in the U.S. has ________

A) doubled B) grown by a factor of four C) grown by a factor of nine D) grown by a factor of twenty E) declined