A manufacturer has an estimated practical capacity of 90,000 machine hours, and each unit requires two machine hours. The following data apply to a recent accounting period: Actual variable overhead$ 240,000 Actual fixed overhead$ 442,000 Actual machine hours worked 88,000 Actual finished units produced 42,000 Budgeted variable overhead at 90,000 machine hours$ 200,000 Budgeted fixed overhead$ 450,000 Of the following factors, the manufacturer's production volume variance is most likely to have been caused by: A. A wage hike granted to a production supervisor. B. A newly imposed initiative to reduce finished goods inventory levels. C. Acceptance of an unexpected sales order. D. Temporary employment of workers with lower skill levels than originally anticipated.