The level of inventory of a manufactured product has increased by 8,509 units during a period. The following data are also available: Variable Fixed Unit manufacturing costs of the period $10.00 $6.00 Unit operating expenses of the period 4.00 5.00 The effect on operating income if absorption costing is used rather than variable costing would be a a. $51,054 increase b. $51,054 decrease c. $93,599 decrease d. $93,599 increase