Neoclassical economists believe that it is not possible to change GDP without a change in the level of the country's resources

The answer for the blank space is In the Long Run

Explanation:

According to neoclassical economic theory, GDP level depends on many factors, like technology, human capital, land, capital. These factors are the country's resources.

Under this economic view, it is possible to change a country's GDP in the short-run without changing the country's resources because there is always some idle capacity that can be used to the maximum in order to reach full potential GDP. However, this is not enough to make GDP grow in the long-run, because sooner than later, the country's existing resources will run out.

Because of this, only a change in the country's resources: more technology, more capital, more labor, more land, can result in sustainable GDP growth in the long-term.

answer; the federal reserve system;