Final answer:
The cost accounting system in question described as using only unit-based activity-drivers to assign costs is known as a Traditional costing system, which is option (D). It is simpler than Activity-Based Costing but may not always allocate indirect costs as accurately.
Step-by-step explanation:
A cost accounting system that uses only unit-based activity-drivers to assign costs to cost objects is called a Traditional costing system. This system generally assigns overhead costs to products based on a predetermined overhead rate times the actual activity consumed by the product, often measured in terms of machine hours or labor hours. While traditional costing is simpler and easier to implement than other costing methods, it is less accurate than Activity-Based Costing (ABC), which uses multiple cost drivers to allocate indirect costs more precisely. Traditional costing systems tend to work best where a large volume of similar products is produced, and the overhead costs are not a significant proportion of the overall costs. In contrast, businesses with a diverse product range and significant indirect costs might benefit from the detailed focus of an ABC system, which would then be categorized under option (C). The correct answer to this question is option (D) Traditional costing system.