Which of the following is not a hypervisor?

Which of the following is not a hypervisor?

• ESX/ESXi
• Hyper-V
• XenServer
• VirtualCrate 

EXPLANATION

 ESX/ESXi VMware ESXi is an enterprise-class, type-1 hypervisor developed by VMware for deploying and serving virtual computers.Wikipedia

Hyper-V Microsoft Hyper-V, codenamed Viridian and formerly known as Windows Server Virtualization, is a native hypervisor; it can create virtual machines on x86-64 systems running Windows. Starting with Windows 8, Hyper-V superseded Windows Virtual PC as the hardware virtualization component of the client editions of Windows NT. A server computer running Hyper-V can be configured to expose individual virtual machines to one or more networks.Wikipedia

XenServer Xen Project is a hypervisor using a microkernel design, providing services that allow multiple computer operating systems to execute on the same computer hardware concurrently. It was developed by the University of Cambridge and is now being developed by the Linux Foundation with support from Intel.Wikipedia

 VirtualCrate is website