Which of the following is a Type 1 hypervisor?

A Type 1 hypervisor, also known as a bare-metal hypervisor, runs directly on the physical hardware of the host machine without needing a host operating system. This type of hypervisor is efficient as it allows for better resource management and potentially improved performance since it has direct access to the hardware.

Citrix XenServer is a prime example of a Type 1 hypervisor. It is designed to operate independently of the host operating system, directly managing the hardware resources of the physical server for efficient virtualization of multiple operating systems in a secure manner. This makes it particularly suited for enterprise deployments where performance and reliability are critical.

In contrast, the other options listed—such as Virtual Box, VMware Workstation, and VMware Fusion—are Type 2 hypervisors. These run on top of a conventional operating system and therefore may introduce additional overhead, limiting their performance and efficiency compared to Type 1 hypervisors.