The level of inventory of a manufactured product has increased by 8,497 units during a period. The following data are also available: Variable Fixed Unit manufacturing costs of the period Unit operating expenses of the period $14.00 $3.00 1.00 4.00 The effect on operating income if variable costing is used rather than absorption costing would be a(n) Oa. $25,491 increase Ob. $59,479 decrease Oc. $59,479 increase Od. $25,491 decrease