An organization has multiple AWS accounts under AWS Organizations. Each account hosts VPCs, EC2 instances, and containers. The compliance team runs a security tool in each VPC on EC2 instances and aggregates results into a dedicated compliance account. All compliance resources are tagged with costCenter=compliance. The company needs an accurate cost calculation for those security tools so the compliance team’s account can be charged. What should a solutions architect do?

The correct option leverages AWS Cost and Usage Reports (CUR) and tag activation for accurate cost allocation. Activating the user-defined tag costCenter in the management account ensures that this tag is applied consistently across all member accounts for billing purposes. CUR provides the most granular cost data, including a breakdown by activated tags, making it ideal for precise cost allocation. Delivering CUR to an S3 bucket in the management account centralizes cost data. The second option is incorrect because while CUR is good, manually fetching and computing costs with a Lambda function is less efficient than using the built-in tag breakdown feature of CUR. The third option is incorrect because activating tags in member accounts does not guarantee organization-wide consistency for billing, and it implies a manual report generation rather than leveraging the automated CUR. The fourth option is incorrect because AWS Trusted Advisor does not provide detailed billing summaries broken down by user-defined tags for cost allocation.