Which type of virtualization allows for multiple virtual machines to run on a single physical machine by using a software layer that separates the hardware? 

  Hypervisor-based virtualization enables multiple virtual machines (VMs) to run on a single physical machine by creating a virtualized environment where hardware resources are separated from the operating system through a software layer called a hypervisor . This type of virtualization is commonly used in data centers for optimizing resource use and consolidating workloads. The hypervisor can be Type 1 (bare-metal) , running directly on hardware, or Type 2 (hosted) , running on an operating system. Why other options are wrong: a) Server-based virtualization : This term is not commonly used in virtualization terminology. It could refer to virtualizing servers, but it is not as specific as hypervisor-based virtualization. c) Application virtualization : This refers to running applications in a virtual environment, isolating them from the underlying OS, not hardware virtualization. d) Storage virtualization : This abstracts physical storage into a virtual storage pool, different from VM virtualization. e) Network virtualization : This abstracts network resources, creating virtual networks, but it does not deal with running multiple VMs on a single machine.