Final answer:
The first stage in CAIS involves the collection of cost data in an organized way using an accounting system.
Step-by-step explanation:
The first stage in CAIS (Cost Accounting Information System) is the collection of cost data in an organized way by means of an accounting system. This involves gathering and recording information about costs incurred in a business operation. For example, the accounting system may track direct costs like raw materials and labor as well as indirect costs like overhead expenses. This data is essential for analyzing and managing costs effectively.