A company has a complex AWS environment with hundreds of linked accounts under AWS Organizations. The CFO wants to allocate costs to specific business units (BUs). However, many resources are shared across BUs, such as Transit Gateways and central logging buckets. How can the Solutions Architect provide accurate cost allocation for both dedicated and shared resources?

Implement AWS Cost Categories to group accounts by BU. Use AWS Application Cost Profiler for shared compute resources, and distribute shared infrastructure costs using Cost Categories split rules.

Apply mandatory tags to all resources. Use AWS Cost Explorer to filter by tags. Shared resources cannot be split, so allocate them to the IT department.

Create separate AWS Organizations for each BU. Migrate resources to the respective organizations to ensure strict billing boundaries.

Use AWS Budgets to set limits per BU. Export the Cost and Usage Report (CUR) to Amazon Athena and write custom SQL queries to estimate shared resource usage.