Final answer:
The cost function of a single-product firm is likely to be either linear or quadratic, depending on whether the firm experiences constant or changing marginal costs of production.
Step-by-step explanation:
The cost function of a single-product firm is typically a function that represents the total cost of production as a function of the quantity of output produced. Since you did not provide a specific cost function, I will provide a general response based on common cost function forms. While several types of functions could theoretically represent a cost function, including linear, quadratic, exponential, and even trigonometric, among the choices provided, the most likely types of functions used to represent the cost function of a firm are either Linear (A) or Quadratic (B). This is because costs often have a fixed component and a variable component that can change based on the levels of production output. Linear cost functions are the simplest form and imply that the marginal cost of producing an additional unit of output is constant. On the other hand, Quadratic cost functions incorporate the idea of increasing or decreasing marginal costs, which can be more realistic as it accounts for efficiencies or inefficiencies at different levels of production.