Which of the following is a measure of economic growth that is most useful for measuring changes in the overall size of an economy? a. growth in nominal gdpb. decreases in the rate of unemploymentc. increases in real gdpreal gdp per capitaa. cannot grow more rapidly than real gdp. b. cannot grow more slowly than real gdp. c. can grow either more slowly or more rapidly than real gdp. given the annual rate of economic growth, the "rule of 72" allows one toa. determine the accompanying rate of inflation. b. calculate the size of the gdp gap. c. calculate the number of years required for real gdp to double.