In the Richer Countries, Over the Past Two Centuries

In the richer countries, over the past two centuries:

A) physical capital has increased significantly, but not human capital.
B) physical capital has steadily increased, while human capital first increased and then decreased.
C) human capital has increased significantly, but not physical capital.
D) physical and human capital have both increased significantly.
E) physical and human capital have both increased significantly, but the increase in physical capital has caused almost all of the growth in output.