Final answer:
The correct comparison of cost data for a company that planned for 48,000 unit sales but sold 60,000 units should be based on 60,000 units of activity to accurately reflect cost performance and resource use.
Step-by-step explanation:
When a company plans to sell 48,000 units but sells 60,000 units, the most appropriate comparison of the cost data associated with the sales would be by a budget based on 60,000 units of activity. This is because the comparison should reflect the actual level of activity to provide an accurate picture of costs per unit, budget variances, and to help in making decisions about resource allocation and cost control going forward. Comparing to a level of activity that didn't occur (such as the original 48,000 units or any other figure like 54,000) might provide a misleading cost per unit and wouldn't reflect the true cost performance or resource use of the business at the higher sales volume.