The average fixed cost curve a. always declines with increased levels of output. b. always rises with increased levels of output. c. declines as long as it is above marginal cost. d. declines as long as it is below marginal cost.

a. always declines with increased levels of output.

Explanation: the average fixed cost curve graphically illustrates or shows the relation between average fixed cost a firm incurs in the short-run production of a good or service, and the quantity produced. The average fixed cost curve always declines with increases in the level of output resulting in a negatively sloped curve. This is to say that the average fixed cost is relatively high at smaller quantities of output, which then declines as the level of production increases--the more output increases, the more average fixed cost declines. Why this occurs is that a given fixed cost is spread over an increasingly larger quantity of output and as such, firms can profitably charge a lower price with increased output.