Refer to Figures $11.7-11.9$ on pages 367 and $369 .$ The lines in the following three graphs show the average relationship between the initial level of real GDP per capita and the growth rate of real GDP per capita for three groups of countries over a given time period. Match each group of countries with the graph that best depicts the relationship between the initial level of real GDP per capita and the growth rate of real GDP per capita for that group.
a. All countries for which statistics are available, $1960-2011$
b. United States, Western Europe, Canada, and Japan, $1990-2014$
c. Current high-income countries, $1960-2011$