Separating Private Returns to Capital from Social Returns to Capital

Multiple Choice

Separating private returns to capital from social returns to capital, that is, the idea that investment in capital may have positive spillover effects as new ideas and new ways of doing things can be easily copied by others, was first advocated by

A) Robert Barro
B) Robert Lucas
C) Robert Samuelson
D) Paul Solow
E) Paul Romer