The pro GDP growth policy of saving and investment has larger returns in relatively lower-income countries than higher income ones. This phenomena is called the catch-up effect, but what is true of the return to physical capital that causes this catch-up effect to exist? O the return to physical capital has diminishing marginal returns O the return to physical capital is consistently high O the return to physical capital is greater than the return to human capital O physical capital is more expensive in higher income countries than in lower income countries.