At 9,000 direct labor hours, the flexible budget for indirect materials is $27,000. If $28,000 of indirect materials costs are incurred at 9,200 direct labor hours, the flexible budget report should show the following difference for indirect materials:
(a)$1,000 unfavorable.
(b)$1,000 favorable.
(c)$400 favorable.
(d)$400 unfavorable.