The level of inventory of a manufactured product has increased by 7,627 units during a period. The following data are also available: Variable Fixed Unit manufacturing costs of the period $13.00 $7.00 Unit operating expenses of the period 3.00 2.00 The effect on operating income it variable costing is used rather than absorption costing would be a(n) Oa. 553.39 decrease b. 553.389 increase Oc. 568,64) increase Od 56.643 de