What term describes the relationship between income levels and saving rates?

The relationship between income levels and saving rates is described by the Consumption Function. This concept illustrates how consumer spending and saving habits change as income levels vary. The Consumption Function typically suggests that as income increases, consumption will also increase, although not necessarily at the same rate. Consequently, higher income levels often correspond with increased savings, reflecting the portion of income that is not spent.

In contrast, disposable income refers specifically to the amount of money individuals have for spending and saving after taxes have been deducted. While it plays a role in determining the Consumption Function, it does not encompass the broader relationship between income levels and saving rates.

Income distribution relates to how income is shared among individuals or groups within an economy, focusing more on equity and disparity rather than the specific relationship between income and savings.

The Investment Function addresses how investments are influenced by factors like interest rates and business profitability, rather than how personal income correlates with savings behavior.

Thus, the correct choice is the Consumption Function, as it directly captures the dynamic relationship between changes in income and the resulting effects on both consumption and savings.