Your subscription contains a resource group named RG1 and the identities shown in an accompanying table. You assign Group4 the Contributor role for RG1. Which identities can you add to Group4 as members?

You can add User1 to Group4 because User1 is a user object. Group1, Group2, and Group3 are groups, and Azure Active Directory (Azure AD) does not allow nesting groups within other groups for role assignments. While you can add users to groups, you cannot add groups to other groups when those groups are used for role-based access control (RBAC) assignments in this manner. Therefore, only individual user accounts like User1 can be direct members of Group4 for the purpose of inheriting the Contributor role on RG1.