Steep Enterprises machines heavy-duty brake rotors that are used on commercial airliners. Steep's management developed the following standard costs: Standard direct labor hours per rotor 2.5 Standard variable overhead rate per direct labor hour $8.00 Actual activity for October Actual variable overhead costs incurred Actual direct labor hours Actual rotors machined $144,300 11,100 3,500 What is the variable manufacturing overhead efficiency variance in Oct O A. $18,800 unfavorable O B. $18,800 favorable O c. $55,500 favorable OD. $55,500 unfavorable