Answer:
The correct answer is A) the additional revenue a firm earns by employing one additional unit of labor.
Step-by-step explanation:
The marginal product of labor is the additional product that is obtained when the amount of labor used is increased by one unit. The marginal product is the variation that PT experiences when using an additional unit of factor.
In the specific case of human capital, we talk about marginal labor productivity. Marginal productivity is an input to determine marginal income.