The correct answer is D. all of the above.
A. Increase in product diversity: As the number of products increases, it becomes more difficult to track costs accurately. This is because each product may have its own unique set of costs, and it can be difficult to allocate indirect costs across multiple products.
B. Increase in indirect costs: Indirect costs are costs that cannot be easily traced to a specific product or service. As the number of indirect costs increases, it becomes more difficult to allocate them accurately. This can lead to inaccurate costing, which can impact pricing and profitability.
C. Product market competitions: As competition in the product market increases, businesses need to find ways to reduce costs in order to remain competitive. This can lead to a focus on refining costing systems in order to identify and eliminate unnecessary costs.
In conclusion, all of the factors listed above can accelerate the process of refining a costing system.