To meet the technical requirements for User1, to which contoso.com group should User1 be added?

User1 needs to manage all aspects of the domain, which requires the highest level of administrative privileges. The Domain Admins group grants full control over all domain controllers and Active Directory objects within the domain, making it the appropriate choice. Account Operators can only manage user and group accounts, not the entire domain. Schema Admins can modify the Active Directory schema, a very specific and high-level task not typically needed for general domain management. Backup Operators can only back up and restore files and folders, not manage the domain.