Final answer:
The marginal product of labor refers to the change in output resulting from adding an additional unit of labor, which depends on the capital and technology available to workers.
Step-by-step explanation:
The correct answer to the student's question, 'The marginal product of labor is the _____,' is C. change in output resulting from adding an additional unit of labor. This term is used to describe the additional output that a firm produces by adding one more worker, or worker hour, to the production process. When considering a homogeneous labor market, where workers have the same background, experience, and skills and exert equal effort, the marginal product of labor is primarily dependent on the capital and technology available to workers.
It is important to distinguish the marginal product of labor from other similar concepts. It is not the change in labor necessary to produce an additional unit of output (option A) nor is it the cost of additional labor (option B). Additionally, it is separate from the change in revenue (option D), which relates to the value of the additional output if it were sold, or what is known as the value of the marginal product or marginal revenue product.