How does the development and diffusion of cell phone technology illustrate the principles of New Growth Theory?

• A. It proves that government intervention is unnecessary for technological progress.
• B. It highlights the diminishing returns of physical capital investment.
• C. It shows that technological advancements are limited to the firms that develop them.
• D. It demonstrates how technological change can drive economic growth and how knowledge capital can lead to increasing returns for the entire economy.

Answer: (D)