Which hypervisor type is installed directly on the hardware of the host machine?

The correct answer is that the hypervisor type installed directly on the hardware of the host machine is a Type 1 hypervisor.

Type 1 hypervisors, also known as bare-metal hypervisors, run directly on the physical hardware without the need for an underlying operating system. This allows them to provide better performance, scalability, and a higher level of security compared to Type 2 hypervisors, which operate on top of an existing operating system. Because Type 1 hypervisors have direct access to hardware resources, they can manage multiple virtual machines (VMs) more efficiently.

In contrast, Type 2 hypervisors rely on a host operating system to access the hardware. This can introduce additional overhead and potential inefficiencies, as they are essentially running as an application within the host OS environment.

Regarding the other answer choices, while "open source" and "proprietary" can describe the licensing models of hypervisors, they do not indicate whether they are Type 1 or Type 2. A hypervisor can be either type and still fall into one of these licensing categories. Thus, they are not relevant to identifying the type of hypervisor that interacts directly with hardware.