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: Standard DL hours per tub Standard variable overhead rate per DL hour Standard variable overhead cost per unit $5.00 $15.00 Actual variable overhead costs Actual DL hours Actual variable overhead cost per machine hour $11,550 2,100 $5.50 Actual tubs produced 1,300 OA. $1,050 favorable B. $9,000 favorable O C. $9,000 unfavorable O D. $1,050 unfavorable