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