The Upton Company employs a standard costing system in which variable overhead is assigned to production based on direct labour hours. Data for the month of February include the following: - Variable manufacturing overhead cost incurred: $48,700 - Total variable overhead variance: $300F - Standard hours allowed for actual production: 7,000 - Actual direct labour hours worked: 6,840 The variable overhead efficiency variance is: a. $950U b. $740F c. $430U d. $1,120F