Which of the following is the most probable reason a company would experience an unfavorable labor rate variance and a favorable labor efficiency variance?

a. The mix of workers assigned to the particular job was heavily weighted towards the use of higher paid, experienced individuals.

b. The mix of workers assigned to the particular job was heavily weighted towards the use of new relatively low paid, unskilled workers.

c. Because of the production schedule, workers from other production areas were assigned to assist this particular process.

d. Defective materials caused more labor to be used in order to produce a standard unit.