To ensure that traffic uses global VNet peering instead of ExpressRoute private peering, you should add a user-defined route to the subnets route table. According to 2, global VNet peering allows virtual networks across regions to communicate using private IP addresses as if they were in the same region. However, if there is an existing ExpressRoute private peering between two regions that also have global VNet peering enabled, traffic will prefer ExpressRoute over global VNet peering by default. To override this behavior and force traffic to use global VNet peering instead of ExpressRoute private peering for a specific subnet or virtual network gateway connection, you need to add a user-defined route with a next hop type of Virtual Network Peering.

To ensure that the backup operation for a database in an availability group using Azure Backup Server runs successfully, you should add the Sysadmin role to the system account on the SQL Server instance. The system account on the SQL Server instance must have the Sysadmin role to perform backup operations. So the correct answer is B. Add the Sysadmin role to the system account on the SQL Server instance.
You can find more information about Azure Backup Server and its requirements in the official Microsoft documentation.

To resolve the problem reported by User2, you need to assign an Azure AD Premium P1 license to User2. User2 is a member of the warehouse group, which is enabled for the self-service password reset (SSPR) feature. However, User2 cannot register for SSPR because they do not have a valid license that supports SSPR. To use SSPR, a user must have one of the following licenses: Azure AD Premium P1, Azure AD Premium P2, Enterprise Mobility + Security (EMS) E3 or EMS E5. By assigning an Azure AD Premium P1 license to User2, you can enable them to use the SSPR feature and reset their password without contacting the helpdesk