The production manager of a company, in an effort to gain a promotion, negotiated a new labor contract with the factory employees that required them to bear a greater percentage of benefit costs than before, thus bringing down the cost of direct labor to the company. Shortly afterward, several experienced and highly skilled workers resigned, and were replaced by new employees whose work was very slow during their training period. At the end of the quarter, the company's profits fell $10\%.$ This would produce $a(n)$

unfavorable direct materials cost variance

favorable direct labor cost variance

favorable direct labor efficiency variance

unfavorable direct materials efficiency variance