Which of the following engines is responsible for storing user and group information?

The correct choice is the Personalization Engine, which is responsible for storing user and group information within the Appian platform. This engine manages the personal settings, user preferences, role assignments, and group memberships that are crucial for tailoring user experiences in applications. Through the Personalization Engine, Appian can access and maintain data related to individual users and their respective roles in the system, allowing for dynamic and personalized functionalities based on user input and group affiliations.

The other engines listed serve different purposes. The Email Notification Engine focuses on sending out email notifications to users based on system events or user actions. The Collaboration Statistics Engine tracks and analyzes user activity and engagement within the collaboration features of the platform. The Content Engine, on the other hand, is responsible for storing and retrieving documents and files within the Appian environment. Each of these engines has its specialized role, but only the Personalization Engine directly manages user and group information.