Answer:
labor
Step-by-step explanation:
Theoretically, the law of diminishing returns could apply to the three factors of production (labor, land and capital), but it is generally used to analyze the amount of production that will be gained by adding additional units of labor. Usually additional units of labor tend to produce diminishing levels of output, e.g. a single extra worker will be able to produce 40 units per day, while another extra worker will only produce 37 units per day.