Answer: D. Accumulation of human capital and technological innovation.
Explanation:
Endogenous growth theory is the belief that to achieve economic growth, there must be an incorporation of technological innovation, human capital, and knowledge or education. These factors are endogenous or internal.
Human capital encompasses all unseen qualities of people such as knowledge and skills that can be harnessed during labor to further economic growth.
The theory also stresses that investment into these internal factors would yield long-run or continuous returns. For example, new advances in technology would lead to new opportunities for economic growth.