Which AWS service or feature allows users to create new AWS accounts, group multiple accounts to organize workflows, and apply policies to groups of accounts?

Explanations:

AWS Identity and Access Management (IAM) is used for managing access to AWS services and resources securely. It allows you to create users, groups, and roles, but it does not provide features for creating new AWS accounts or organizing multiple accounts.

AWS Trusted Advisor is a service that provides real-time guidance to help you provision your resources following AWS best practices. It offers checks related to cost optimization, performance, security, fault tolerance, and service limits, but it does not manage accounts or group policies.

AWS CloudFormation is a service for modeling and setting up AWS resources so that you can spend less time managing those resources and more time focusing on your applications. It does not allow for account creation or management.

AWS Organizations allows users to create new AWS accounts, group multiple accounts for organizational purposes, and apply policies at the organizational level, enabling centralized management of billing, access, and compliance across those accounts.