The level of inventory of a manufactured product has increased by 7,783 units during a period. The following data are also available: Variable Fixed Unit manufacturing costs of the period $12.00 $4.00 Unit operating expenses of the period 1.00 5.00 The effect on operating income if absorption costing is used rather than variable costing would be a Oa. 370,047 increase Ob. 531,132 increase Oc. 531,132 decrease Od 570,047 decrease