The physical server that runs the hypervisor is known as the:

The physical server that runs the hypervisor is known as the:

• Master
• Trunk
• Host
• Root 

EXPLANATION

A hypervisor is a program that allows multiple operating systems to share a single hardware host. The hypervisor runs on a host server, which is the physical server that provides the resources used these virtual operating systems. https://en.wikipedia.org/wiki/Hypervisor
The term "Host" comes from the biological relationship between a host and a parasite. http://www.businessdictionary.com/definition/host-computer.html