Part 4 of 5 O Points: 0 of 1 ll in the blanks to make the following statements correct. As more of a variable factor is used in combination with given quantities of fixed factors, the marginal product of the variable factor will eventually decrease. This hypothesis is known as the w of diminishing marginal returns . The change in total output resulting from the use of one additional unit of the variable factor is called the marginal product If the average product and marginal product curves are plotted on a graph, the AP curve is rising as long as the MP curve lies above the AP curve. The AP curve is falling when the MP curve s below the AP curve. Consider a firm whose only variable factor is labour. As the firm hires more labour, the point of diminishing marginal productivity sets in once the marginal product of labour reaches a