Which of the following mathematical expressions is used to calculate budgeted variable overhead cost rate per output unit? A. Budgeted input allowed per output unit + Budgeted variable overhead cost rate per input unit B. Budgeted input allowed per output unit x Budgeted variable overhead cost rate per input unit C. Budgeted output allowed per input unit x Budgeted variable overhead cost rate per input unit O D. Budgeted output allowed per input unit + Budgeted variable overhead cost rate per input unit