A) Identify ONE way that the data in the chart illustrate global economic differences between countries in the late twentieth century. b) Identify ONE similarity (other than GDP per capita) that might account for the low life expectancies of some of the world's countries, as displayed in the chart. c) Explain ONE way in which longer life expectancies in some of the world's countries, as displayed in the chart, have led to new political, economic, or social problems.