Final answer:
According to the new growth theory, the most crucial factor in economic growth is technology, as it drives innovations that enhance productivity and overall economic development. While human and physical capital play significant roles, it's the technological progress that makes the most considerable impact.
Step-by-step explanation:
The new growth theory emphasizes the role of different factors in a country's economic growth. Among the options given, technology is typically considered the most crucial factor for U.S. economic growth. Studies have found that new ways of doing things, which encompasses technological innovation, are immensely important. Although growth in human capital and physical capital can explain a significant portion of economic growth, it's the advancements in technology that often drive growth to a larger extent. Moreover, these three factors—technology, human capital, and physical capital—work in synergy. Technology enables new production processes, which can then be actualized through investments in physical capital and are often utilized by a more educated and skilled labor force.
While entrepreneurship is critical for economic development, it is not the primary focus of the new growth theory, which concentrates on the aforementioned factors. It's the interplay of technological innovation, education, workforce skills, and investment in new capital that powers significant economic advancement.