The level of inventory of a manufactured product has increased by 7,903 units during a period. The following data are also available: Variable Fixed Unit manufacturing costs of the period $13.00 $5.00 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 a(n)

a.$39,515 decrease

b.$55,321 increase

c.$55,321 decrease

d.$39,515 increase