Select the incorrect statement concerning standard costs and job order costing.

a$.$

A standard cost system determines product cost by using predetermined norms in the inventory accounts for prices and$/$or quantities of cost components.

b$.$

Standard cost variances can be computed for actual$-$to$-$standard differences regardless of whether standards have been established for both quantities and prices or for prices or rates only.

c$.$

Under GAAP, standard cost job order systems may not substitute for actual or normal costing systems.

d$.$

Standards can be used in a job order cost system only if a company typically engages in jobs that produce fairly similar products.