A company is making plastic sandboxes out of various grades of plastic. If this company has an unfavorable once labor rate variance, this probably means that: a. It is using higher skilled workers, which should lead to an unfavorable DL efficiency variance. b. It is using lower skilled workers, which should lead to an unfavorable DL efficiency variance. c. It is using lighter skilled workers, which should lead to a favorable DL efficiency variance. d. It is using lower skilled workers, which should lead to a favorable DL efficiency variance. e. None of the above