Costing system, which classify cost into cost categories in a way when an expense is incurred in process is called

The correct answer is: C. process costing system.

A process costing system is a costing system that is used to track the costs of production in a manufacturing environment where a large number of identical units are produced. In a process costing system, costs are accumulated by department or process, and then assigned to units of product based on the number of units produced in each department or process.

A conversion expense costing system is a costing system that is used to track the costs of converting raw materials into finished goods. Conversion costs include direct labor and manufacturing overhead.

An inventory costing system is a costing system that is used to track the costs of inventory. Inventory costing systems can be either perpetual or periodic. A perpetual inventory system tracks the costs of inventory on a continuous basis, while a periodic inventory system only tracks the costs of inventory at the end of an accounting period.

A job costing system is a costing system that is used to track the costs of individual jobs or batches of products. In a job costing system, costs are accumulated by job or batch, and then assigned to units of product based on the actual costs incurred for each job or batch.

Here is a table that summarizes the key differences