Final answer:
The marginal product of the tenth worker is five units, as it is the additional output produced by the company when hiring the tenth worker, raising total output from 90 to 95 units.
Step-by-step explanation:
The marginal product of labor is the additional output produced by adding one more worker to the production process. In the scenario provided, the company's output increased from 90 units with nine workers to 95 units when a tenth worker was employed. This makes the marginal product of the tenth worker equal to the additional five units produced (95 - 90 = 5). Therefore, the correct answer to the question is A) Five units.
Marginal product is important in understanding the contribution of each additional unit of labor. Often, as more workers are added, there is an initial increase in marginal product due to factors such as specialization and division of labor; however, this can be followed by a decrease due to the law of diminishing marginal product, which occurs when there is too much labor for the available capital or technology, leading to inefficiencies.