A. Purchasing and sales personnel rarely can influence material usage by production workers.

B. Industrial engineers are involved in designing product and setting the standards of material usage, thus bearing a part of the responsibility for the efficiency of material usage. However, sales personnel rarely can influence material usage by production workers.

C. Industrial engineers are involved in designing product and setting the standards of material usage, thus bearing a part of the responsibility for the efficiency of material usage. Production workers are those who actually convert materials into the finished product and directly responsible for efficiency of material usage. Therefore, both of these parties will have some responsibility for the materials efficiency variance.

D. Industrial engineers are involved in designing product and setting the standards of material usage, thus bearing a part of the responsibility for the efficiency of material usage. However, purchasing personnel rarely can influence material usage by production workers.