Riverside Manufacturing designs and manufactures bathtubs for home and commercial applications. Riverside recorded the following data for its commercial bathtub production line during the month of March: 5 Standard DL hours per tub Standard variable overhead rate per DL hour Standard variable overhead cost per unit $6.00 $30.00 Actual variable overhead costs Actual DL hours Actual variable overhead cost per machine hour $21,375 2,850 $7.50 Actual tubs produced 1,500 What is the variable manufacturing overhead efficiency variance in March? O A. $4,275 favorable O B. $27,900 unfavorable O C. $4,275 unfavorable OD. $27,900 favorable