The following information was collected for one of the costs at Demetra Manufacturing Corporation over the past two years. Assuming that there has been no change in the cost structure over the last two years and this activity is within the relevant range, this cost at Demetra would best be described as a: This year. Units Produced Total Cost 5.000 6.000 $125.000 $147,000 Last year....... Select one: O a. fixed cost. b. true variable cost. 0 O c. step-variable cost. d. mixed cost.