The level of inventory of a manufactured product has increased by 8,912 units during a period. The following data are also available: Variable Fixed Unit manufacturing costs of the period $13.00 $8.00 Unit operating expenses of the period 2.00 2.00 The effect on operating income if variable costing is used rather than absorption costing would be an) O. 564.016 create Ob 500,120 dece Oc564096 decrease Od 30.120 increase