Derf Corporation uses a standard cost system in which it applies manufacturing overhead on the basis of standard direct labor-hours. Two direct labor-hours are required for each unit produced. The denominator activity was set at 13,800 units. Manufacturing overhead was budgeted at $138,000 for the period; 20 percent of this cost was fixed. The 26,800 hours worked during the period resulted in production of 12,600 units. Variable manufacturing overhead cost incurred was $112,700 and fixed manufacturing overhead cost was $27,700. The variable overhead efficiency variance for the period was: Multiple Choice $2,400 Unfavorable $6,400 Unfavorable $5,500 Unfavorable $100 Unfavorable