To run multiple operating systems on a single machine, you would need a hypervisor. A hypervisor is software that creates and manages virtual machines, allowing you to run multiple operating systems concurrently on a single physical host. Examples of hypervisors include VMware, VirtualBox, and Microsoft Hyper-V.
The other options listed—firmware, multitasker, and OS switcher—are not specifically designed for the purpose of running multiple operating systems simultaneously on the same hardware.