The law of diminishing returns describes the:

A) relationship between total costs and total revenues.
B) profit-maximizing position of a firm.
C) relationship between resource inputs and product outputs in the short run.
D) relationship between resource inputs and product outputs in the long run.

The law of diminishing returns refers to the phenomenon where adding more and more of a specific input (such as labor or capital) to a fixed amount of other inputs (such as land or raw materials) will eventually cause the marginal product (i.e. additional output) of that input to decline, resulting in a diminishing return. This relationship only applies in the short run, as firms can adjust their fixed inputs in the long run to avoid diminishing returns.