For deploying the Veeam Agent on Amazon EC2 instances running Windows and Linux operating systems without direct network access from the Veeam Distribution Server, the appropriate type of Protection Group to use is D: Cloud machines. The "Cloud machines" protection group type in Veeam Backup & Replication is specifically designed for protecting cloud-based workloads, including instances in public cloud environments like Amazon EC2. This protection group type allows the Veeam Agent to be deployed and managed remotely, even when the Veeam Distribution Server cannot directly access the instances over the network. It facilitates centralized management of backup tasks for cloud instances, ensuring that the EC2 instances are adequately protected as per management's request, despite the network accessibility constraints.