Mexico is a. a poor country, and over the past century its rate of economic growth has been higher than that of the United States. b. a poor country, and over the past century its rate of economic growth has been lower than that of the United States. c. a middle-income country, and over the past century its rate of economic growth has been higher than that of the United States. d. a middle-income country, and over the past century its rate of economic growth has been lower than that of the United States.