The level of inventory of a manufactured product has increased by 7,651 units during a period. The following data are also available: Variable Fixed Unit manufacturing costs of the period Unit operating expenses of the period $12.00 4.00 $8.00 3.00 The effect on operating income if variable costing is used rather than absorption costing would be an) a $84,161 increase b. $61,208 decrease c. $84,161 decrease Qd. $61,208 increase