Concept:Economic development requires capital formation, which is achieved through savings and investment.
Explanation:When people save a part of their income, funds become available for investment.
Investment in productive assets like machinery, factories, and infrastructure increases production capacity.
Higher production leads to more goods and services, higher employment, and higher national income.
This process accelerates economic development over time.
Encouraging consumption or importing consumer goods does not build productive capacity.
Early marriage does not contribute to the growth of capital resources.
Therefore, policies that promote savings and investment are most effective for speeding up development.
Answer:D. Savings and investment.