A​ company's production department was experiencing a high defect rate on the assembly​ line, which was slowing down production and causing wastage of valuable direct materials. The production manager decided to purchase a higher grade of materials that would be more​ reliable, but he was worried that the cost of the new materials might negatively affect operating income. This would produce​ a(n) ________.A. unfavorable direct materials cost variance
B. unfavorable direct materials efficiency variance
C. favorable direct labor cost variance
D. favorable direct labor efficiency variance