Answer: (D) Increase in labor productivity
Explanation:
When the labor productivity get increased then, it lead to sustain the long run economical growth. When there is high productivity then, the cost of the product or goods gets lower. When there is increase in the demand then it lead to increase the revenue.
The economical growth is basically refers as when the economy raise the productivity rate then it trend to increase the growth of the national overall result. Technological advancement is one of the important factor in development of the Long run growth.