According to classical economists, what primarily determines the price level?

The primary determinant of the price level, according to classical economists, is closely linked to the concepts surrounding aggregate supply at full employment. Classical theory posits that in the long run, the economy operates at full employment and that the total production capacity of the economy ultimately sets the framework for price levels.

Classical economists believe that the price level is determined by the quantity of money in circulation and its relation to the economy's output of goods and services. When the economy is at full employment, the supply side indicates that any changes in the money supply will directly influence price levels rather than output levels, which are considered constant. Therefore, aggregate supply at full employment becomes a critical foundation for determining the overall price level in classical economics.

The other options touch on aspects relevant to economic conditions but do not focus on the underlying relationship of supply, demand, and money supply that classical economists emphasize. Total production in the economy and levels of national output and income certainly correlate with economic health, but they do not serve as primary determinants for the price level in the classical view. Instead, it's the aggregate supply at full employment, intertwined with the money supply, that sets the stage for how price levels fluctuate within the economy.