33. During the last three months, a manufacturer incurred an unfavorable labor efficiency variance. The least likely cause of this variance is: A. substantial materials were purchased at a discount at a previously unused supplier's liquidation for one week, only half of the workforce, those with the highest seniority, were B. called in to work C. a second production line with all new personnel was started D. the cost-of-living adjustment for the three-month period was $.10 more per hour than expected E. none of the above