The profitability of each separate job or product can only be tracked using which product costing system?

Job order costing is the correct answer because it allows businesses to track the profitability of individual jobs or products by assigning specific costs to each unique job. This system is particularly useful in environments where products are made to order or where services are provided on a task-by-task basis. Each job can incur different costs for materials, labor, and overhead, enabling detailed analysis of the profitability of that specific job.

In contrast, process costing, which is more suited to industries where products are mass-produced in a continuous flow, averages costs over a large number of identical units and does not provide the same level of detail for individual jobs. Average unit costing also shares similarities in its approach, focusing on an average cost across units and not allowing for specific profitability tracking per job. Profitability costing is not a standard term used in accounting practice, and while it may imply tracking profits, it does not outline a specific methodology for cost assignment or tracking like job order costing does. Therefore, tracking the profitability of each separate job is effectively accomplished through the job order costing system.