Final answer:
A work-in-process inventory file comprises all job cost sheets, detailing materials, labor, and overhead costs for each partially completed unit of product. It is crucial for tracking production expenses and managing budgets.
Step-by-step explanation:
A work-in-process inventory file is a collection of documentation related to the costs associated with production. The correct answer to what it comprises is all job cost sheets, which are records detailing the materials, labor, and overhead costs for each job or unit of product that is partially completed. These sheets provide a comprehensive view of the ongoing costs associated with production, enabling businesses to track expenses and manage budgeting effectively.