Strait Co. manufactures office furniture. During the most productive month of the year, 3,200 desks were manufactured at a total cost of $82,900. In the month of lowest production the company made 1,280 desks at a cost of $61,600. Using the high-low method of cost estimation, total fixed costs are Oa. $47,412 Ob. $21,300 Oc. $82,900 Od. 561,600