Final answer:
Marginal product is the change in total product divided by the change in the quantity of labor.
Step-by-step explanation:
According to the provided information, marginal product is defined as the additional output or change in the total product caused by the addition of one more unit of variable input, in this case, the number of workers. It is calculated by dividing the change in total product by the change in the quantity of labor. Therefore, option a) The change in total product divided by the change in the quantity of labor is the correct answer. In the "law" of diminishing marginal returns, the marginal product initially increases when more of an input is employed, keeping the other input constant.