What role did the national bank play in the economy?

The national bank played a crucial role in offering capital for expansion, which was essential for the development of various sectors within the economy. By providing loans and credit facilities, the bank enabled businesses to invest in new projects, expand their operations, and enhance their productivity. This access to capital not only stimulated economic growth but also helped to facilitate trade and commerce across regions.

The national bank's ability to manage currency and interest rates further contributed to the stability and growth of the economy. This financial support was particularly important during periods of economic transformation, such as the Industrial Revolution, where growth in industries required significant investment in infrastructure and machinery.

Contextually, while labor for industries, agricultural growth, and regulation of transportation are important economic factors, they are not the primary functions of the national bank. The bank's central role was to ensure that businesses had the financial resources necessary to grow and succeed, making the option regarding capital for expansion the most accurate representation of the national bank’s impact on the economy.