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 8,400 units. Manufacturing overhead was budgeted at $126,000 for the period; 20 percent of this cost was fixed. The 16,000 hours worked during the period resulted in production of 7,650 units. Variable manufacturing overhead cost incurred was $100,500 and fixed manufacturing overhead cost was $25,300. The variable overhead efficiency variance for the period was:

$4,500 Unfavorable

$4,200 Unfavorable

$2,250 Unfavorable

$100 Unfavorable