Which of the following best defines fixed cost?
a. It is the periodic cost that varies with the production or sales revenue of the firm.
b. It is the sum of all costs that are not directly attributable to a cost object.
c. It is the cost that does not change as the output is increased or decreased.
d. It is the sum of marginal costs over all units produced.
Answer: c. It is the cost that does not change as the output is increased or decreased.