The purchasing manager was able to bring down the cost of direct materials by purchasing direct materials of a slightly lower grade quality than the company had used previously. The lower grade of direct materials, however, meant a higher defect rate on the assembly line and a higher waste of direct materials during production, which in turn lowered operating income. This would have led to a(n) A) unfavorable direct materials efficiency variance B) unfavorable direct materials cost variance OC) favorable direct labor efficiency variance OD) favorable direct labor cost variance