The following standards for variable overhead have been established for a company that makes only one product: Standard hours per unit of output.. Standard variable overhead rate. The following data pertain to operations for the last month: Actual hours Actual total variable overhead cost. Actual output. What is the variable overhead efficiency variance for the month? Select one: 6.3 hours $18.65 per hour 8,600 hours $157.380 1.100 units 0 a. $31,146 U O b. $30,561 U O c. $28,136 U O d. $2,426 U