An enterprise has 50 AWS accounts under AWS Organizations. They want to implement a chargeback model where each business unit (BU) pays for its own AWS usage. However, some resources like Transit Gateway and central databases are shared. How can the architect provide accurate cost visibility and chargeback capabilities?

Use AWS Cost Explorer to filter by account ID. Manually calculate shared costs using an Excel spreadsheet.

Implement AWS Cost Categories. Define rules to map accounts to BUs, and use split charge rules to distribute shared costs proportionally.

Use AWS Budgets to set limits per BU. Tag shared resources with multiple BU tags.

Enable Cost and Usage Reports (CUR). Write a custom AWS Lambda function to parse the CSV and allocate costs.