Kennedy Manufacturing produces a single product. The standard cost card for the product follows: Direct materials (4 yards times $5 per yard). $20 Direct labor (1 5 hours times $10 per hour) $15 Variable manufacturing overhead (1 5 hrs times $4 per hour) $6 During a recent period the company produced 1,200 units of product Various costs associated with the production of these units are given below: Direct materials purchased (6.000 yards) $28.500 Direct materials used in production 5.000 yards Direct labor cost incurred (2, 100 hours) $17.850 Variable manufacturing overhead cost incurred $10,080 The company records all variances at the earliest possible point in time. Variable manufacturing overhead costs are applied to products on the basis of standard direct hours. The variable overhead efficiency variance for the period is: Select one: a $1,200 U b $1,440 U c. $1,200 F d. $1,440 F