Harris Enterprises machines heavy-duty brake rotors that are used on commercial airliners. The company's management developed the following standard costs: Standard direct labor hours per rotor Standard overhead rate per direct labor hour 1.6 $11.50 Actual activity for October: Actual overhead costs incurred Actual direct labor hours $162,000 10,800 3,500 Actual rotors machined What is the variable manufacturing overhead efficiency variance in October? OA. $59,800 favorable OB. $59,800 unfavorable OC. $37,800 unfavorable D. $37,800 favorable