Kronstedt Corporation has a standard cost system in which it applies manufacturing overhead to products on the basis of standard machine-hours (MHs). The company has provided the following data for the most recent month: Budget Level of Activity....... 6,100 MHs Actual Level of Activity....... 6,300 MHs Cost formula for variable overhead cost.... $6.70 per MH Budgeted fixed manufacturing overhead cost.... $42,000 Actual Total variable overhead.......... $41,580 Actual total fixed manufacturing overhead.... $45,000 What was the variable overhead rate variance for the month? A. $710 unfavorable B. $1,340 unfavorable C. $630 favorable D. $3,000 unfavorable