Use this information to answer the question that follow. The standard costs and actual costs for factory overhead for the manufacture of 2,600 units of actual production are as follows: Standard Costs Fixed overhead (based on 10,000 hours) 3 hours per unit @ $0.78 per hour Variable overhead 3 hours per unit @ $1.90 per hour Actual Costs Total variable cost, $18,000 Total fixed cost, $8,100 The total factory overhead cost variance is O a. $6,612 favorable b. $4,896 unfavorable c. $3,180 unfavorable d. $4,896 favorable