Predetermined overhead rates in traditional costing are often based on

a) direct labor cost for job order costing and machine hours for process costing.

Explanation:

As we know that the predetermined overhead rate is the rate which is to be computed by considering the total estimated manufacturing overhead cost and the estimated activity level i. e machine hours, etc

Under the traditional costing, in case of job order costing it ts based on direct labor cost while in the process costing it is based on machine hours

Hence, first option is correct