Which AWS service should the company use to aggregate and manage all accounts?

Explanations:

AWS Billing and Cost Management allows you to manage billing and costs but does not provide account aggregation or management features across multiple accounts.

AWS Organizations enables the management of multiple AWS accounts from a single master account, allowing for centralized billing, policy management, and resource sharing among accounts.

AWS Identity and Access Management (IAM) is focused on managing user permissions and access control within a single AWS account, not on managing multiple accounts.

AWS Resource Access Manager allows sharing of resources across accounts but does not provide account management or aggregation features like AWS Organizations does.