Which API is used for managing users and groups in Tableau Server?

The correct choice is the REST API because it is specifically designed for performing a variety of administrative functions in Tableau Server, including managing users and groups. The REST API enables developers to automate server management tasks, allowing for actions such as creating, updating, or deleting users and groups within Tableau Server. It provides a comprehensive interface for interacting with the server's resources in a programmatic way, making it essential for administrators looking to streamline their workflows and ensure effective user management.

The other options serve different purposes. The Document API is primarily used for managing Tableau documents such as workbooks and data sources and focuses on content management rather than user administration. The Extensions API allows developers to build interactive extensions for dashboards but does not handle user management functionalities. The Hyper API is focused on creating and managing Hyper data extracts, thus not applicable for user and group management tasks in Tableau Server.