How does gross domestic product (gdp) differ from gross national income (gni)? a. gdp counts the number of citizens in a country, while gni counts the number of citizens abroad. b. gdp measures how happy people are in a country, while gni measures how happy they are internationally. c. gdp is used by nasa to measure eroding coastlines, while gni is used by the fbi to monitor criminal activity across borders. d. gdp measures the money that a country makes in its own land, while gni measures the money it makes in other countries and at home.