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 Actual activity for October: Actual overhead costs incurred Actual direct labor hours Actual rotors machined 2 $9.75 $123,60010,3004,100 What is the variable manufacturing overhead efficiency variance in October? A. $20,475 favorable B. $20,475 unfavorable C. $23,175 unfavorable D. $23,175 favorable