To ensure that User1 can deploy virtual machines and manage virtual networks, you need to assign an RBAC role that grants the necessary permissions to perform these tasks. The solution must also use the principle of least privilege, which means that you should only grant the minimum level of access required to accomplish the goal.
Based on these requirements, the best RBAC role to assign to User1 is D.
Virtual Machine Contributor. This role allows User1 to create and manage virtual machines, disks, snapshots, and network interfaces. It also allows User1 to connect virtual machines to existing virtual networks and subnets. However, it does not allow User1 to create or delete virtual networks or subnets, or to access the virtual machines themselves. This role follows the principle of least privilege by limiting User1's access to only the resources and actions that are relevant to deploying virtual machines and managing virtual networks1.