6. ( 2 point) At the end of the accounting period Stanley, Inc. reports operating income of $24,000, a contribution margin of $12 per unit, and a fixed overhead rate of $4 per unit. Under variable costing, if this company produces 50 more units of inventory without selling them, then operating income: a. will increase by $400 b. will increase by $200 c. will decrease by $600 d. will decrease by $400 e. will decrease by $200 f. will increase by $600 g. will not be affected h. Cannot be determined