What is the difference between a service firm and a manufacturer?

A.the cost of a job for a service firm consists of direct labor and indirect costs and a cost of a job for a manufacturer consists of direct materials, direct labor and manufacturing overhead

B.a service firms largest cost of a job is labor where as a typical manufacturer direct labor is not the largest component but only part of the total cost of a job.

C.service firms allocate indirect period costs and a manufacturer allocates manufacturing overhead

D.All of the above are differences between a service firm and a manufacturer